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Table of Contents

IP Routing Protocols Commands

IP Routing Protocols Commands

Cisco's implementation of the Internet Protocol (IP) suite provides all major services contained in the TCP/IP specifications.

Use the commands in this chapter to configure and monitor the IP routing protocols. For IP routing protocol configuration information and examples, refer to the "Configuring IP Routing Protocols" chapter of the Router Products Configuration Guide.

area (authentication)

Use the area router configuration command with the authentication keyword to enable authentication for an OSPF area. The no form of this command with the authentication keyword removes the area's authentication specification. The command no area area-id (no other keywords) removes the specified area from the router's configuration.

area area-id authentication
no area
area-id authentication
no area
area-id
Syntax Description
area-id Identifier (ID) of the area for which authentication is to be enabled. The identifier can be specified as either a decimal value or an IP address.
Default

Type 0 authentication (no authentication)

Command Mode

Router configuration

Usage Guidelines

Specifying authentication for an area sets the authentication to Type 1 (simple password) as specified in RFC 1247. If this command is not included in the configuration file, authentication of Type 0 (no authentication) is assumed.

The authentication type must be the same for all routers in an area. The authentication password for all OSPF routers on a network must be the same if they are to communicate with each other via OSPF. Use the ip ospf authentication-key interface configuration command to specify this password.

Example

The following example mandates authentication for areas 0 and 36.0.0.0 of OSPF routing process 201. Authentication keys are also provided.

interface ethernet 0 ip address 131.119.251.201 255.255.255.0 ip ospf authentication-key adcdefgh ! interface ethernet 1 ip address 36.56.0.201 255.255.0.0 ip ospf authentication-key ijklmnop ! router ospf 201 network 36.0.0.0 0.255.255.255 area 36.0.0.0 network 131.119.0.0 0.0.255.255 area 0 area 36.0.0.0 authentication area 0 authentication
Related Commands

ip ospf authentication-key
area
(default-cost)
area
(stub)

area (default-cost)

Use the area router configuration command with the default-cost keyword to specify a specific cost for the default summary route sent into a stub area. Use the no form of this command to remove the assigned default route cost.

area area-id default-cost cost
no area
area-id default-cost cost
Syntax Description
area-id Identifier (ID) for the stub area. The identifier can be specified as either a decimal value or as an IP address.
cost Cost for the default summary route used for a stub area. The acceptable value is a 24-bit number.
Default

1

Command Mode

Router configuration

Usage Guidelines

This command is used only on an area border router attached to a stub area.

There are two stub area router configuration commands: the stub and default-cost options of the area command. In all routers attached to the stub area, the area should be configured as a stub area using the stub option of the area command. Use the default-cost option only on an area border router attached to the stub area. The default-cost option provides the metric for the summary default route generated by the area border router into the stub area.

Example

The following example assigns a default-cost of 20 to stub network 36.0.0.0:

interface ethernet 0 ip address 36.56.0.201 255.255.0.0 ! router ospf 201 network 36.0.0.0 0.255.255.255 area 36.0.0.0 area 36.0.0.0 stub area 36.0.0.0 default-cost 20
Related Commands

area (authentication)
area
(stub)

area (range)

Use the area router configuration command with the range keyword to consolidate and summarize routes at an area boundary. Use the no form of this command to disable this function for the specified area.

area area-id range address mask
no area
area-id range address mask
Syntax Description
area-id Identifier (ID) of the area about which routes are to be summarized. It can be specified as either a decimal value or as an IP address.
address IP address.
mask IP mask.
Default

Disabled

Command Mode

Router configuration

Usage Guidelines

This command is only used with area border routers. It is used to consolidate or summarize routes for an area. The result is that a single summary route is advertised to other areas by the area border router. Routing information is condensed at area boundaries. External to the area, a single route is advertised for each address range. This is called route summarization.

Multiple area router configuration commands specifying the range option can be configured. Thus, OSPF can summarize addresses for many different sets of address ranges.

Example

The following example specifies one summary route to be advertised by the area border router to other areas for all subnets on network 36.0.0.0 and for all hosts on network 192.42.110.0:

interface ethernet 0 ip address 192.42.110.201 255.255.255.0 ! interface ethernet 1 ip address 36.56.0.201 255.255.0.0 ! router ospf 201 network 36.0.0.0 0.255.255.255 area 36.0.0.0 network 192.42.110.0 0.0.0.255 area 0 area 36.0.0.0 range 36.0.0.0 255.0.0.0 area 0 range 192.42.110.0 255.255.255.0

area (stub)

Use the area router configuration command with the stub keyword to define an area as a stub area. Use the no form of this command to disable this function for the specified area.

area area-id stub
no area
area-id stub
Syntax Description
area-id Identifier (ID) for the stub area. The identifier can be either a decimal value or an IP address.
Default

None

Command Mode

Router configuration

Usage Guidelines

This command must be configured on all routers in the stub area. Use the area router configuration command with the default-cost option to specify the cost of a default internal router sent into a stub area by an area border router.

There are two stub area router configuration commands: the stub and default-cost options of the area router configuration command. In all routers attached to the stub area, the area should be configured as a stub area using the stub option of the area command. Use the default-cost option only on an area border router attached to the stub area. The default-cost option provides the metric for the summary default route generated by the area border router into the stub area.

Example

The following example assigns a default cost of 20 to stub network 36.0.0.0:

interface ethernet 0 ip address 36.56.0.201 255.255.0.0 ! router ospf 201 network 36.0.0.0 0.255.255.255 area 36.0.0.0 area 36.0.0.0 stub area 36.0.0.0 default-cost 20
Related Commands

area (authentication)
area
(default-cost)

area (virtual-link)

Use the area router configuration command with the virtual-link keyword and the optional parameters to define an OSPF virtual link. Use the no form of this command to remove the virtual link.

area area-id virtual-link router-id [hello-interval number-of-seconds]
[retransmit-interval number-of-seconds]
[transmit-delay number-of-seconds]
[dead-interval number-of-seconds]
[authentication-key 8-bytes-of-password]

no area area-id virtual-link router-id [hello-interval number-of-seconds]
[retransmit-interval number-of-seconds]
[transmit-delay number-of-seconds]
[dead-interval number-of-seconds]
[authentication-key 8-bytes-of-password]
Syntax Description
area-id Area ID assigned to the transit area for the virtual link. This can be either a decimal value or a valid IP address. There is no default.
router-id Router ID associated with the virtual link neighbor. The router ID appears in the show ip ospf display. It is internally derived by each router from the router's interface IP addresses. This value must be entered in the format of an IP address. There is no default.
hello-interval (Optional.) Number of seconds between the Hello packets that the router sends on an interface.
number-of-seconds (Optional.) Unsigned integer value to be advertised in the router's Hello packets. The value must be the same for all routers attached to a common network. The default is 10 seconds.
retransmit-interval (Optional.) Number of seconds between link state advertisement retransmissions for adjacencies belonging to the interface.
number-of-seconds (Optional.) Expected round-trip delay between any two routers on the attached network. The value must be greater than the expected round-trip delay. The default is 5 seconds.
transmit-delay (Optional.) Estimated number of seconds it takes to transmit a link state update packet on the interface.
number-of-seconds (Optional.) Integer value that must be greater than zero. Link state advertisements in the update packet have their age incremented by this amount before transmission. The default value is 1 second.
dead-interval (Optional.) Number of seconds that a router's Hello packets are not seen before its neighbors declare the router down.
number-of-seconds

(Optional.) Unsigned integer value. The default is four times the Hello interval. As with the Hello interval, this value must be the same for all routers attached to a common network.
authentication-key (Optional.) Specific password to be used by neighboring routers.
8-bytes-of-password (Optional.) Any continuous string of characters that you can enter from the keyboard up to 8 bytes in length. This string acts as a key that will allow the authentication procedure to generate or verify the authentication field in the OSPF header. This key is inserted directly into the OSPF header when originating routing protocol packets. A separate password can be assigned to each network on a per-interface basis. All neighboring routers on the same network must have the same password to be able to route OSPF traffic. There is no default value.
Default

See "Syntax Description" for various defaults.

Command Mode

Router configuration

Usage Guidelines

In OSPF, all areas must be connected to a backbone area. If the connection to the backbone is lost, it can be repaired by establishing a virtual link.

The smaller the Hello interval, the faster topological changes will be detected, but more routing traffic will ensue.

The setting of the retransmit interval should be conservative, or needless retransmissions will result. The value should be larger for serial lines and virtual links.

The transmit delay value should take into account the transmission and propagation delays for the interface.

A router will use the specified authentication key only when authentication is enabled for the backbone with the area area-id authentication router configuration command.


Note Each virtual link neighbor must include the transit area ID and the corresponding virtual link neighbor's router ID in order for a virtual link to be properly configured. Use the show ip ospf EXEC command to see the router ID of a router.
Example

The following example establishes a virtual link with default values for all optional parameters:

router ospf 201 network 36.0.0.0 0.255.255.255 area 36.0.0.0 area 36.0.0.0 virtual-link 36.3.4.5
Related Command

area (authentication)

area-password

Use the area-password router configuration command to configure the IS-IS area authentication password. The no area-password command disables the password.

area-password password
no area-password [
password]
Syntax Description
password Password you assign.
Default

None

Command Mode

Router configuration

Usage Guidelines

This password is inserted in Level 1 (station router level) LSPs, CSNPs, and Partial Sequence Number PDUs (PSNP).

Example

The following example assigns an area authentication password:

router isis area-password angel
Related Command

domain-password

autonomous-system (EGP)

Use the autonomous-system global configuration command to specify the local autonomous system that the router resides in for EGP. To remove the AS number, use the no autonomous-system command.

autonomous-system local-as
no autonomous-system local-as
Syntax Description
local-as Local autonomous system (AS) number to which the router belongs.
Default

None

Command Mode

Global configuration

Usage Guidelines

Before you can set up EGP routing, you must specify an autonomous system number. The local AS number will be included in EGP messages sent by the router.

Example

The following sample configuration specifies an autonomous system number of 110:

autonomous-system 110
Related Command

router egp

clear arp-cache

Use the clear arp-cache EXEC command to remove all dynamic entries from the ARP cache and to clear the fast-switching cache.

clear arp-cache
Syntax Description

This command has no arguments or keywords.

Command Mode

EXEC

Example

The following example removes all dynamic entries from the ARP cache and clears the fast-switching cache:

clear arp-cache

clear ip bgp

To reset a BGP connection, use the clear ip bgp EXEC command at the system prompt.

clear ip bgp [{* | address}]
Syntax Description
* (Optional.) Resets all current BGP sessions.
address (Optional.) Resets only the identified BGP neighbor.
Command Mode

EXEC

Usage Guidelines

Use this command whenever any of the following changes occur:

Example

The following example shows how to reset all current BGP sessions:

clear ip bgp *
Related Commands

show ip bgp
timers bgp

clear ip route

Use the clear ip route EXEC command to remove one or more routes from the IP routing table.

clear ip route {network [mask] | *}
Syntax Description
network Network or subnet address to remove.
mask (Optional.) Network mask associated with the IP address you wish to remove.
* Remove all entries.
Default

None

Command Mode

EXEC

Example

The following example removes a route to network 132.5.0.0 from the IP routing table:

clear ip route 132.5.0.0
Related Command

show ip route

default-information allowed

Use the default-information allowed router configuration command to control exterior information between IGRP processes. The no default-information allowed in command causes IGRP exterior or default routes to be suppressed when received by an IGRP process. The no default-information allowed out command causes IGRP exterior routes to be suppressed in updates.

default-information allowed {in | out}
no default-information allowed {in | out}
Syntax Description
in Allows IGRP exterior or default routes to be received by an IGRP process.
out Allows IGRP exterior routes to be advertised in updates.
Default

Normally, exterior routes are always accepted and default information is passed between IGRP processes when doing redistribution.

Command Mode

Router configuration

Usage Guidelines

The default network of 0.0.0.0 used by RIP cannot be redistributed by IGRP.

Example

The following example allows IGRP exterior or default routes to be received by the IGRP process in autonomous system 23:

router igrp 23 default-information allowed in

default-information originate (EGP)

Use the default-information originate router configuration command to explicitly configure EGP to generate a default route. The no default-information originate command disables this function.

default-information originate
no default-information originate
Syntax Description

This command has no arguments or keywords.

Default

Disabled

Command Mode

Router configuration

Usage Guidelines

Because EGP can use network 0.0.0.0 as a default route, EGP must be explicitly configured to generate a default route. If the next hop for the default route can be advertised as a third party, it will be included as a third party.

Example

The following example configures EGP to generate a default route:

autonomous system 109 router egp 164 network 131.108.0.0 network 192.31.7.0 neighbor 10.2.0.2 default-information originate

default-information originate (OSPF and IS-IS)

Use the default-information originate router configuration command to generate a default route into an OSPF or IS-IS routing domain. The no default-information originate command disables generation of a default route into the specified OSPF or IS-IS routing domain.

For OSPF:

default-information originate [always] [metric metric-value] [metric-type type-value]
{level-1 | level-1-2 | level-2} [route-map map-name]
no default-information originate [always] [metric metric-value] [metric-type type-value]
{level-1 | level-1-2 | level-2} [route-map map-name]

For IS-IS:

default-information originate [route-map map-name]
no default-information originate
[route-map map-name]
Syntax Description
originate For OSPF, causes the router to generate a default external route into an OSPF domain if the router already has a default route and you want to propagate to other routers. For IS-IS, originates the default route whether or not it resides in the routing table.
always (Optional.) For OSPF, the default route always will be advertised whether or not the router has a default route.
metric metric-value (Optional.) Metric used for generating the default route. If a value is not specified for this option, and no value is specified using the default-metric router configuration command, the default metric value is 10. The value used is specific to the protocol.
metric-type type-value (Optional.) For OSPF, the external link type associated with the default route advertised into the OSPF routing domain. It can be one of two values:

1--Type 1 external route

2--Type 2 external route

If a metric-type is not specified, the router adopts a Type 2 external route.

For IS-IS, it can be one of two values:

internal--IS-IS metric which is < 63.

external--IS-IS metric which is > 64 < 128.

The default is internal.

level-1 For IS-IS only, Level 1 routes are redistributed into other IP routing protocols independently. It specifies if IS-IS advertises network 0.0.0.0 into the Level 1 area.
level-1-2 For IS-IS only, both Level 1 and Level 2 routes are redistributed into other IP routing protocols. It specifies if IS-IS advertises network 0.0.0.0 into both levels in a single command.
level-2 For IS-IS only, Level 2 routes are redistributed into other IP routing protocols independently. It specifies if IS-IS advertises network 0.0.0.0 into the Level 2 subdomain.
route-map map-name (Optional.) Routing process will generate the default route if the route-map is satisfied.
Default

Disabled

Command Mode

Router configuration

Usage Guidelines

Whenever you use the redistribute or the default-information router configuration commands to redistribute routes into an OSPF routing domain, the router automatically becomes an AS boundary router. However, an AS boundary router does not, by default, generate a default route into the OSPF routing domain. The router still needs to have a default route for itself before it generates one, except when you have specified the always keyword.

When you use this command for the OSPF process, the default network must reside in the routing table and you must satisfy the route-map map-name keyword. Use the default-information originate always route-map map-name form of the command when you do not want the dependency on the default network in the routing table.

If a router configured with this command has a route to 0.0.0.0 in the routing table, IS-IS will originate an advertisement for 0.0.0.0 in its LSPs.

Examples

In the following configuration, the router is forced to generate a default external route into an
IS-IS domain:

router isis ! BGP routes will be distributed into IS-IS redistribute bgp 120 ! access list 2 is applied to outgoing routing updates distribute-list 2 out ! metric of 60 is specified for default router redistributed into IS-IS ! routing domain. default-information originate metric 60 ! access list 2 defined as giving access to network 100.105.0.0 access-list 2 permit 100.105.0.0 0.0.255.255

The following example specifies a metric of 100 for the default route redistributed into the OSPF routing domain and an external metric type of Type 1:

router ospf 109 redistribute igrp 108 metric 100 subnets default-information originate metric 100 metric-type 1
Related Commands

isis metric
redistribute

default-metric

Use the default-metric router configuration command to set default metric values for the RIP, EGP, BGP, IGRP, and enhanced IGRP routing protocols. Use the no default-metric command to remove the metric value and return to the default state.

default-metric number
no default-metric
number
Syntax Description
number Default metric value appropriate for the specified routing protocol.
Default

Built-in, automatic metric translations, as appropriate for each routing protocol

Command Mode

Router configuration

Usage Guidelines

This command is used in conjunction with the redistribute router configuration command to cause the current routing protocol to use the same metric value for all redistributed routes. A default metric helps solve the problem of redistributing routes with incompatible metrics. Whenever metrics do not convert, using a default metric provides a reasonable substitute and enables the redistribution to proceed.

In BGP, this sets the INTER_AS metric.

Example

The following example shows a router in autonomous system 109 using both the RIP and the IGRP routing protocols. The example advertises IGRP-derived routes using the RIP protocol and assigns the IGRP-derived routes a RIP metric of 10.

router rip default-metric 10 redistribute igrp 109
Related Command

redistribute

default-metric (IGRP)

Use this form of the default-metric router configuration command to set metrics for IGRP. Use the no default-metric command to remove the metric value and return to the default state.

default-metric bandwidth delay reliability loading mtu
no default-metric
bandwidth delay reliability loading mtu
Syntax Description
bandwidth Minimum bandwidth of the route in kilobits per second.
delay Route delay in tens of microseconds.
reliability Likelihood of successful packet transmission expressed as a number between 0 and 255 (255 is 100 percent reliability).
loading Effective bandwidth of the route in kilobits per second.
mtu Minimum Maximum Transmission Unit (MTU) size of the route.
Default

Built-in, automatic metric translations

Command Mode

Router configuration

Usage Guidelines

IGRP metric defaults have been carefully set to work for a wide variety of networks. Take great care in changing these values.

Automatic metric translations for IGRP are only supported when redistributing from IGRP or static.

Example

The following example takes redistributed RIP metrics and translates them into IGRP metrics with values as follows: bandwidth = 1000, delay = 100, reliability = 250, loading = 100, and mtu =1500.

router igrp 109 network 131.108.0.0 redistribute rip default-metric 1000 100 250 100 1500
Related Command

redistribute

distance bgp

Use the distance bgp router configuration command to allow the use of three possible administrative distances--external, internal, and local--that could be a better route to a node. Use the no distance bgp command to reset these values to their defaults.

distance bgp external-distance internal-distance local-distance
no distance bgp
Syntax Description
external-distance Administrative distance for BGP external routes. External routes are routes for which the best path is learned from a neighbor external to the autonomous system. Acceptable values are from 10 to 255.
internal-distance Administrative distance for BGP internal routes. Internal routes are those routes that are learned from another BGP entity within the same autonomous system. Acceptable values are from 10 to 255.
local-distance Administrative distance for BGP local routes. Local routes are those networks listed with a network router configuration command, often as back doors, for that router or for networks that are being redistributed from another process. Acceptable values are from 10 to 255.
Default

external-distance = 20
internal-distance = 200
local-distance = 200

Command Mode

Router configuration

Usage Guidelines

An administrative distance is a rating of the trustworthiness of a routing information source, such as an individual router or a group of routers. Numerically, an administrative distance is an integer between 0 and 255. In general, the higher the value, the lower the trust rating. An administrative distance of 255 means the routing information source cannot be trusted at all and should be ignored.

Use this command if another protocol is known to be able to provide a better route to a node than was actually learned via external BGP, or if some internal routes should really be preferred by BGP.


Note Changing the administrative distance of BGP internal routes is considered dangerous and is not recommended. One problem that can arise is the accumulation of routing table inconsistencies, which can break routing.
Example

In the following example, internal routes are known to be preferable to those learned through the IGP, so the administrative distance values are set accordingly:

router bgp 109 network 131.108.0.0 neighbor 129.140.6.6 remote-as 123 neighbor 128.125.1.1 remote-as 47 distance bgp 20 20 200

distance

Use the distance router configuration command to define an administrative distance. Use the no distance command with the appropriate arguments to remove a distance definition.

distance weight [address mask [access-list-number]] [ip]
no distance weight [address mask [access-list-number]] [ip]
Syntax Description
weight Integer from 10 to 255 for the administrative distance. (Values 0 through 9 are reserved for internal use.) Used alone, the argument specifies a default administrative distance that the router uses when no other specification exists for a routing information source.
address (Optional.) IP address.
mask (Optional.) In dotted-decimal format which bits, if any, to ignore in the address value; a set bit in the mask argument instructs the router to ignore the corresponding bit in the address value.
access-list-number (Optional.) Number of a standard IP access list to be applied to incoming routing updates.
ip (Optional.) IP-derived routes for IS-IS. Can be applied independently for IP routes and ISO CLNS routes.
Default

See values in Table 1-1

Command Mode

Router configuration

Usage Guidelines

Numerically, an administrative distance is an integer between 0 and 255. In general, the higher the value, the lower the trust rating. An administrative distance of 255 means the routing information source cannot be trusted at all and should be ignored.

When the optional access list number is used with this command, it is applied when a network is being inserted into the routing table. This allows filtering of networks according to the IP address of the router supplying the routing information. This could be used, as an example, to filter out possibly incorrect routing information from routers not under your administrative control.

The order in which you enter distance commands can affect the assigned administrative distances in unexpected ways (see "Example" for further clarification).

Weight values are also subjective; there is no quantitative method for choosing weight values.

Default administrative distances are shown in Table 1-1.


Default Administrative Distance
Route Source Default Distance
Connected interface 0
Static route 1
External BGP 20
IGRP 100
OSPF 110
IS-IS 115
RIP 120
EGP 140
Internal BGP 200
Unknown 255

The show ip protocols EXEC command displays the default administrative distance for a specified routing process.

Example

In the following example, the router igrp global configuration command sets up IGRP routing in AS number 109. The network router configuration commands specify IGRP routing on networks 192.31.7.0 and 128.88.0.0. The first distance router configuration command sets the default administrative distance to 255, which instructs the router to ignore all routing updates from routers for which an explicit distance has not been set. The second distance command sets the administrative distance for all routers on the Class C network 192.31.7.0 to 90. The third distance command sets the administrative distance for the router with the address 128.88.1.3 to 120.

router igrp 109 network 192.31.7.0 network 128.88.0.0 distance 255 distance 90 192.31.7.0 0.0.0.255 distance 120 128.88.1.3 0.0.0.0

distribute-list (in)

Use this form of the distribute-list router configuration command to filter networks received in updates. (Not supported in IS-IS.) Use the no form of this command to change or cancel the filter.

distribute-list access-list-number in [interface-name]
no distribute-list
access-list-number in [interface-name]
Syntax Description
access-list-number Standard IP access list number. The list explicitly specifies which networks are to be received and which are to be suppressed.
in Applies the access list to incoming routing updates.
interface-name (Optional.) Interface on which the access list should be applied to incoming updates. If no interface is specified, the access list will be applied to all incoming updates.
Default

Disabled

Command Mode

Router configuration

Example

The following example causes only two networks to be accepted by a RIP routing process: network 0.0.0.0 (the RIP default) and network 131.108.0.0.

access-list 1 permit 0.0.0.0 access-list 1 permit 131.108.0.0 access-list 1 deny 0.0.0.0 255.255.255.255 router rip network 131.108.0.0 distribute-list 1 in
Related Commands

A dagger (+) indicates that the command is documented in another chapter.

access-list +
distribute-list (out)
redistribute

distribute-list (out)

Use this form of the distribute-list router configuration command to suppress networks from being advertised in updates. Use the no form of this command to cancel this function.

distribute-list access-list-number out {interface-name | routing-process}
no distribute-list
access-list-number out {interface-name | routing-process}
Syntax Description
access-list-number Standard IP access list number. The list explicitly specifies which networks are to be sent and which are to be suppressed in routing updates.
out Applies the access list to outgoing routing updates.
interface-name Name of a particular interface. Does not apply to OSPF.
routing-process Name of a particular routing process, or static or connected.
Default

Disabled

Command Mode

Router configuration

Usage Guidelines

When redistributing networks, a routing process name can be specified as an optional trailing argument to the distribute-list command. This causes the access list to be applied to only those routes derived from the specified routing process. After the process-specific access list is applied, any access list specified by a distribute-list command without a process name argument will be applied. Addresses not specified in the distribute-list command will not be advertised in outgoing routing updates.


Note To filter networks received in updates, use the distribute-list in command.
Examples

The following example would cause only one network to be advertised by a RIP routing process: network 131.108.0.0.

access-list 1 permit 131.108.0.0 access-list 1 deny 0.0.0.0 255.255.255.255 router rip network 131.108.0.0 distribute-list 1 out

In the following example, access list 1 is applied to outgoing routing updates and IS-IS is enabled on interface Ethernet 0. Only network 131.131.101.0 will be advertised in outgoing IS-IS routing updates.

router isis redistribute ospf 109 distribute-list 1 out interface Ethernet 0 ip router isis access-list 1 permit 131.131.101.0 0.0.0.255
Related Commands

A dagger (+) indicates that the command is documented in another chapter.

access-list +
distribute-list (in)
redistribute

domain-password

Use the domain-password router configuration command to configure the IS-IS routing domain authentication password. The no domain-password command disables the password.

domain-password password
no domain-password [
password]
Syntax Description
password Password you assign.
Default

None set

Command Mode

Router configuration

Usage Guidelines

This password is inserted in Level 2 (area router level) LSPs, CSNPs, and Partial Sequence Number PDUs (PSNP).

Example

The following example assigns an authentication password to the routing domain:

router isis domain-password flower
Related Command

area-password

ip address

Use the ip address interface configuration command to specify the IP address on an interface. The no ip address command removes the specified secondary address.

ip address address mask [secondary]
no ip address address
mask [secondary]
Syntax Description
address IP address.
mask IP address mask.
secondary (Optional.) Address to be added as a secondary address.
Default

Disabled

Command Mode

Interface configuration

Usage Guidelines

The optional keyword secondary allows an unlimited number of secondary addresses to be specified. Secondary addresses are treated like primary addresses, except that the system never generates datagrams other than routing updates with secondary source addresses. IP broadcasts and ARP requests are handled properly, as are interface routes in the IP routing table.

Secondary IP addresses can be used in a variety of situations. The following are the most common applications:


Note If any router on a network segment uses a secondary address, all other routers on that same segment must also use a secondary address from the same network or subnet. An inconsistent use of secondary addresses on a network segment can very quickly lead to routing loops.
Example

The following example specifies 131.108.1.27 as the primary address and 192.31.7.17 as a secondary address for interface Ethernet 0:

interface ethernet 0 ip address 131.108.1.27 255.255.255.0 ip address 192.31.7.17 255.255.255.0 secondary

ip as-path access-list

Use the ip as-path access-list global configuration command to define a BGP-related access list. To disable use of the access list, use the no ip as-path access-list command.

ip as-path access-list access-list-number {permit | deny} as-regular-expression
no ip as-path access-list
access-list-number {permit | deny} as-regular-expression
Syntax Description
access-list-number Integer from 1 to 99 that indicates the access list.
permit Permits access for matching conditions.
deny Denies access to matching conditions.
as-regular-expression AS in the access list using a regular expression. See the "Regular Expressions" appendix for information on forming regular expressions.
Default

None

Command Mode

Global configuration

Usage Guidelines

You can specify an access list filter on both inbound and outbound BGP routes. In addition, you can assign weights based on a set of filters. Each filter is an access list based on regular expressions. If the regular expression matches the representation of the autonomous system path of the route as an ASCII string, then the permit or deny condition applies. The AS path does not contain the local AS number. Use the ip as-path access-list global configuration command to define an BGP access list, and the neighbor router configuration command to apply a specific access list.

See the "Regular Expressions" appendix for information on forming regular expressions.

Example

The following example specifies that the BGP neighbor with IP address 128.125.1.1 is not sent advertisements about any path through or from the adjacent AS 123.

ip as-path access-list 1 deny ^123$ ip as-path access-list 1 deny ^123 .* ! The space in the above expression (^123.*) is required. router bgp 109 network 131.108.0.0 neighbor 129.140.6.6 remote-as 123 neighbor 128.125.1.1 remote-as 47 neighbor 128.125.1.1 filter-list 1 out
Related Commands

neighbor distribute-list
neighbor filter-list

ip default-network

Use the ip default-network global configuration command to select a network as a candidate route for computing the gateway of last resort. Use the no default-network command to remove the route.

ip default-network network-number
no ip default-network
network-number
Syntax Description
network-number Number of the network.
Default

If the router has a directly connected interface onto the specified network, the dynamic routing protocols running on that router will generate (or source) a default route. For RIP, this is flagged as the pseudonetwork 0.0.0.0; for IGRP, it is the network itself, flagged as an exterior route.

Command Mode

Global configuration

Usage Guidelines

The router uses both administrative distance and metric information to determine the default route. Multiple ip default-network commands can be given. All candidate default routes, both static (that is, flagged by ip default-network) and dynamic, appear in the routing table preceded by an asterisk.

Examples

The following example defines a static route to network 10.0.0.0 as the static default route:

ip route 10.0.0.0 255.0.0.0 131.108.3.4 ip default-network 10.0.0.0

If the following command was issued on a router not connected to network 129.140.0.0, the router might choose the path to that network as a default route when the network appeared in the routing table:

ip default-network 129.140.0.0
Related Command

show ip route

ip gdp

Use any of the ip gdp interface configuration commands to enable GDP routing on an interface. The no ip gdp command disables GDP routing, with all default parameters.

ip gdp priority number
ip gdp reporttime seconds
ip gdp holdtime seconds
no ip gdp
Syntax Description
priority number Alters the GDP priority; default is a priority of 100. A larger number indicates a higher priority.
reporttime seconds Alters the GDP reporting interval; the default is 5 seconds for broadcast media such as Ethernets, and never for nonbroadcast media such as X.25.
holdtime seconds Alters the GDP default hold time of 15 seconds.
Default

priority = 100
reporttime = 5 seconds for broadcast media; 0 for nonbroadcast media
holdtime = 15 seconds

Command Mode

Interface configuration

Usage Guidelines

When enabled on an interface, GDP updates report the primary and secondary IP addresses of that interface.

Example

In the following example, GDP is enabled on interface Ethernet 1 with a report time of 10 seconds, and priority and hold time set to their defaults (because none are specified):

ip gdp reporttime 10

ip irdp

Use the variations of the ip irdp interface configuration command to enable ICMP Router Discovery Protocol (IRDP) processing on an interface. The no ip irdp command disables IRDP routing on the specified interface.

ip irdp
ip irdp multicast
ip irdp holdtime seconds
ip irdp maxadvertinterval seconds
ip irdp minadvertinterval seconds
ip irdp preference number
ip irdp address address [number]
no ip irdp
Syntax Description
multicast Use the multicast address (224.0.0.1) instead of IP broadcasts.
holdtime seconds Length of time in seconds advertisements are held valid. Default is three times the maxadvertinterval value. Must be greater than maxadvertinterval and cannot be greater than 9000 seconds.
maxadvertinterval seconds Maximum interval in seconds between advertisements. The default is 600 seconds.
minadvertinterval seconds Minimum interval in seconds between advertisements. The default is 0.75 times the maxadvertinterval. If you change the maxadvertinterval value, this value defaults to three-quarters of the new value.
preference number Router's preference value. The allowed range is -231 to 231. The default is 0. A higher value increases the router's preference level. You can modify a particular router so that it will be the preferred router to which others home.
address address [number] IP address (address) to proxy-advertise, and optionally, its preference value (number).
Default

When enabled, IRDP uses these defaults:

Command Mode

Interface configuration

Usage Guidelines

If you change maxadvertinterval, the other two values also change, so it is important to change maxadvertinterval first before changing either holdtime or minadvertinterval.

The ip irdp multicast command allows for compatibility with Sun Microsystems Solaris, which requires IRDP packets to be sent out as multicasts. Many implementations cannot receive these multicasts; ensure end host ability before using this command.

Example

The following example illustrates how to set the various IRDP processes:

! enable irdp on interface Ethernet 0 interface ethernet 0 ip irdp ! send IRDP advertisements to the multicast address ip irdp multicast ! increase router preference from 100 to 50 ip irdp preference 50 ! set maximum time between advertisements to 400 secs ip irdp maxadvertinterval 400 ! set minimum time between advertisements to 100 secs ip irdp minadvertinterval 100 ! advertisements are good for 6000 seconds ip irdp holdtime 6000 ! proxy-advertise 131.108.14.5 with default router preference ip irdp address 131.108.14.5 ! proxy-advertise 131.108.14.6 with preference of 50 ip irdp address 131.108.14.6 50

ip ospf authentication-key

Use the ip ospf authentication-key interface configuration command to assign a password to be used by neighboring routers that are using OSPF's simple password authentication. The no ip ospf authentication-key command removes any previously assigned OSPF password.

ip ospf authentication-key password
no ip ospf authentication-key
Syntax Description
password Any continuous string of characters that can be entered from the keyboard up to 8 bytes in length.
Default

Null

Command Mode

Interface configuration

Usage Guidelines

The password created by this command is used as a "key" that is inserted directly into the OSPF header when the router originates routing protocol packets. A separate password can be assigned to each network on a per-interface basis. All neighboring routers on the same network must have the same password to be able to exchange OSPF information.


Note A router will use this key only when authentication is enabled for an area with the area authentication router configuration command.
Example

In the following example, the authentication key is enabled with the string yourpass:

ip ospf authentication-key yourpass
Related Command

area authentication

ip ospf cost

Use the ip ospf cost interface configuration command to explicitly specify the cost of sending a packet on an interface. The no ip ospf cost command resets the path cost for an interface to the default value.

ip ospf cost cost
no ip cost
Syntax Description
cost Unsigned integer value expressed as the link state metric. The range is from 1 to 65535.
Default

See "Usage Guidelines"

Command Mode

Interface configuration

Usage Guidelines

Unlike IGRP, you must set this metric manually using this command, if you need to change the default. Changing the bandwidth does not change the link cost.

The link state metric is advertised as the link cost in the router's router link advertisement. We do not support Type of Service (TOS), so you can assign only one cost per interface.

In general, the path cost is calculated as follows:

108 ÷ Bandwidth

Using the above formula, the default path costs were calculated as noted in the following list. If these values do not suit your network, you can use your own method of calculating path costs.

Example

The following example sets the interface cost value to 65:

ip ospf cost 65

ip ospf dead-interval

Use the ip ospf dead-interval interface configuration command to set the number of seconds that a router's Hello packets must not have been seen before its neighbors declare the router down. The no ip ospf dead-interval command resets the length of time to the default value.

ip ospf dead-interval number-of-seconds
no ip ospf dead-interval
Syntax Description
number-of-seconds Unsigned integer value that specifies the interval; must be the same for all nodes on the network.
Default

Four times the interval set for the ip ospf hello-interval command

Command Mode

Interface configuration

Usage Guidelines

The interval is advertised in the router's Hello packets. This value must be the same for all routers on a specific network.

Example

The following example sets the OSPF dead interval to 60 seconds:

interface ethernet 1 ip ospf dead-interval 60
Related Command

ip ospf hello-interval

ip ospf hello-interval

Use the ip ospf hello-interval interface configuration command to specify the interval between Hello packets that the router sends on the interface. The no ip ospf hello-interval command resets the interval to the default value.

ip ospf hello-interval number-of-seconds
no ip ospf hello-interval
Syntax Description
number-of-seconds Unsigned integer that specifies the interval in seconds. The value must be the same for all nodes on a specific network.
Default

10 seconds

Command Mode

Interface configuration

Usage Guidelines

This value is advertised in the router's Hello packets. The smaller the Hello interval, the faster topological changes will be detected, but more routing traffic will ensue. This value must be the same for all routers on a specific network.

Example

The following example sets the interval between Hello packets to 15 seconds:

interface ethernet 1 ip ospf hello-interval 15
Related Command

ip ospf dead-interval

ip ospf-name-lookup

Use the ip ospf-name-lookup global configuration command to configure OSPF to look up Domain Name System (DNS) names for use in all OSPF show EXEC command displays. The
no ip ospf-name-lookup command disables the feature.

ip ospf-name-lookup
no ip ospf-name-lookup
Syntax Description

This command has no arguments or keywords.

Default

Disabled

Command Mode

Global configuration

Usage Guidelines

This feature makes it easier to identify a router because it is displayed by name rather than by its router ID or neighbor ID.

Example

The following example configures OSPF to look up DNS names for use in all OSPF show EXEC command displays:

ip ospf-name-lookup
Sample Display

The following is sample output of the show ip ospf database EXEC command, for example, once you have enabled the DNS name lookup feature.

Router# show ip ospf database OSPF Router with id (160.89.41.1) (Autonomous system 109) Router Link States (Area 0.0.0.0) Link ID ADV Router Age Seq# Checksum Link count 160.89.41.1 router 381 0x80000003 0x93BB 4 160.89.34.2 neon 380 0x80000003 0xD5C8 2 Net Link States (Area 0.0.0.0) Link ID ADV Router Age Seq# Checksum 160.89.32.1 router 381 0x80000001 0xC117

ip ospf network

Use the ip ospf network interface configuration command to configure the OSPF network type to a type other than the default for a given media. The no ip ospf network command restores the default.

ip ospf network {broadcast | non-broadcast}
no ip ospf network
Syntax Description.
broadcast Sets the network type to broadcast.
non-broadcast Sets the network type to nonbroadcast.
Default

Depends on the network type

Command Mode

Interface configuration

Usage Guidelines

Using this feature, you can configure broadcast networks as nonbroadcast multiaccess networks when, for example, you have routers in your network that do not support multicast addressing. You can also configure nonbroadcast multiaccess networks, such as X.25, Frame Relay, and SMDS, as broadcast networks. This feature saves you from having to configure neighbors.

If this command is issued on an interface that does not allow it, it will be ignored.

Example

The following example sets your OSPF network as a broadcast network:

interface serial 0 ip address 160.89.77.17 255.255.255.0 ip ospf network broadcast encapsulation frame-relay
Related Commands

neighbor (OSPF)
x25-map
frame-relay map

ip ospf priority

Use the ip ospf priority interface configuration command to set the router's priority, which helps determine the designated router for this network. The no ip ospf priority command resets the router priority to the default value.

ip ospf priority number
no ip ospf priority
Syntax Description
number 8-bit unsigned integer that specifies the priority. The range is from 0 to 255.
Default

1

Command Mode

Interface configuration

Usage Guidelines

When two routers attached to a network both attempt to become the designated router; the one with the higher router priority takes precedence. If there is a tie, the router with the higher router ID takes precedence. A router with a router priority set to zero is ineligible to become the designated router or backup designated router. Router priority is only configured for interfaces to multiaccess networks (in other words, not point-to-point networks).

This priority value is used when you configure OSPF for nonbroadcast networks using the neighbor router configuration command for OSPF.

Example

The following example sets the router priority value to 4:

interface ethernet 0 ip ospf priority 4
Related Commands

ip ospf network
neighbor (OSPF)

ip ospf retransmit-interval

To specify the number of seconds between link state advertisement retransmissions for adjacencies belonging to the interface, use the ip ospf retransmit-interval interface configuration command. The no ip ospf retransmit-interval command resets the link state advertisement retransmission interval to the default value.

ip ospf retransmit-interval number-of-seconds
no ip ospf retransmit-interval
Syntax Description
number-of-seconds Number of seconds between retransmissions; it must be greater than the expected round-trip delay between any two routers on the attached network. The range is 1 to 65535 seconds. The default is 5 seconds.
Default

5 seconds

Command Mode

Interface configuration

Usage Guidelines

When a router sends a link state advertisement (LSA) to its neighbor, it keeps the LSA until it receives back the acknowledgment. If it receives no acknowledgment in number -of-seconds, it will retransmit the LSA.

The setting of this parameter should be conservative, or needless retransmission will result. The value should be larger for serial lines and virtual links.

Example

The following example sets the retransmit-interval value to 8 seconds:

interface ethernet 2 ip ospf retransmit-interval 8

ip ospf transmit-delay

Use the ip ospf transmit-delay interface configuration command to set the estimated number of seconds it takes to transmit a link state update packet on the interface. The no ip ospf transmit-delay command resets the estimated transmission time to the default value.

ip ospf transmit-delay number-of-seconds
no ip ospf transmit-delay
Syntax Description
number-of-seconds Integer that specifies the number of seconds it takes to transmit a link state update. The range is 1 to 65535 seconds.
Default

1 second

Command Mode

Interface configuration

Usage Guidelines

Link state advertisements in the update packet must have their age incremented by the amount specified in the number-of-seconds argument before transmission. The value assigned should take into account the transmission and propagation delays for the interface.

If the delay is not added before transmission over a link, the time in which the LSA propagates over the link is not considered. This setting has more significance on very low speed links.

Example

The following example sets the retransmit-delay value to 3 seconds:

interface ethernet 0 ip ospf transmit-delay 3

ip route

Use the ip route global configuration command to establish static routes. The no ip route command removes the static routes.

ip route network [mask ] {address | interface} [distance]
no ip route
Syntax Description
network Internet address of the target network or subnet.
mask (Optional.) Network mask that lets you mask network and subnetwork bits.
address Internet address of the next hop that can be used to reach that network.
interface Network interface to use.
distance (Optional.) An administrative distance.
Default

None

Command Mode

Global configuration

Usage Guidelines

A static route is appropriate when the router cannot dynamically build a route to the destination.

If you specify an administrative distance, you are flagging a static route that can be overridden by dynamic information. For example, IGRP-derived routes have a default administrative distance of 100. To have a static route that would be overridden by an IGRP dynamic route, specify an administrative distance greater than 100. Static routes have a default administrative distance of 1.

Static routes that point to an interface will be advertised via RIP, IGRP, and other dynamic routing protocols, regardless of whether redistribute static commands were specified for those routing protocols. This is because static routes that point to an interface are considered in the routing table to be connected and hence lose their static nature. However, if you define a static route to an interface that is not one of the networks defined in a network command, no dynamic routing protocols will advertise the route unless a redistribute static command is specified for these protocols.

Examples

In the following example, an administrative distance of 110 was chosen. In this case, packets for network 10.0.0.0 will be routed through to the router at 131.108.3.4 if dynamic information with administrative distance less than 110 is not available.

ip route 10.0.0.0 255.0.0.0 131.108.3.4 110

In the following example, packets for network 131.108.0.0 will be routed to the router at 131.108.6.6:

ip route 131.108.0.0 255.255.0.0 131.108.6.6

ip router isis

Use the ip router isis interface configuration command to configure an IS-IS routing process for IP over a specified interface. The no ip router isis command disables IS-IS for IP on the interface.

ip router isis [tag]
no ip router isis
[tag]
Syntax Description
tag (Optional.) Defines a meaningful name for a routing process. If not specified, a null tag is assumed. It must be unique among all IP router processes for a given router. Use the same text for the argument tag as specified in the router isis global configuration command.
Default

None

Command Mode

Interface configuration

Example

The following example specifies IS-IS as an IP routing protocol for a process named Finance, and specifies that the Finance process will be routed on interfaces Ethernet 0 and serial 0:

router isis Finance interface Ethernet 0 ip router isis Finance interface serial 0 ip router isis Finance
Related Command

router isis

ip split-horizon

Use the ip split-horizon interface configuration command to enable the split-horizon mechanism. The no ip split-horizon command turns off the split-horizon mechanism.

ip split-horizon
no ip split-horizon
Syntax Description

This command has no arguments or keywords.

Default

Varies with media

Command Mode

Interface configuration

Usage Guidelines

For all interfaces except those for which either Frame Relay or SMDS encapsulation is enabled, the default condition for this command is ip split-horizon; in other words, the split horizon feature is active. If the interface configuration includes either the encapsulation frame-relay or encapsulation smds interface configuration commands, then the default is for split horizon to be disabled. Split horizon is not disabled by default for interfaces using any of the X.25 encapsulations.


Note For networks that include links over X.25 PSNs, the neighbor router configuration command can be used to defeat the split horizon feature. You can as an alternative explicitly specify the no ip split-horizon command in your configuration. However, if you do so you must similarly disable split horizon for all routers in any relevant multicast groups on that network.

If split horizon has been disabled on an interface and you wish to enable it, use the ip split-horizon command to restore the split horizon mechanism.


Note In general, changing the state of the default for the ip split-horizon command is not recommended, unless you are certain that your application requires making a change in order to properly advertise routes. Remember: If split horizon is disabled on a serial interface (and that interface is attached to a packet-switched network), you must disable split horizon for all routers in any relevant multicast groups on that network.
Example

The following example illustrates a simple example of disabling split horizon on a serial link. In this example, the serial link is connected to an X.25 network:

interface serial 0 encapsulation x25 no ip split-horizon

is-type

Use the is-type router configuration command to configure the IS-IS level at which the router will operate. The no is-type command resets the parameter to the default.

is-type {level-1 | level-1-2 | level-2-only}
no is-type {level-1 | level-1-2 | level-2-only}
Syntax Description
level-1 Router acts as a station router.
level-1-2 Router acts as both a station router and an area router.
level-2-only Router acts as an area router only.
Default

level-1-2

Command Mode

Router configuration

Example

The following example specifies an area router:

router isis is-type level-2-only

isis circuit-type

Use the isis circuit-type interface configuration command to configure the type of adjacency desired for the specified interface. The no isis circuit-type command resets the circuit type to Level l and Level 2.

isis circuit-type {level-1 | level-1-2 | level-2-only}
no isis circuit-type
Syntax Description
level-1 A Level 1 adjacency may be established if there is at least one area address in common between this system and its neighbors.
level-1-2 A Level 1 and 2 adjacency is established if the neighbor is also configured as level-1-2 and there is at least one area in common. If there is no area in common, a Level 2 adjacency is established. This is the default.
level-2-only A Level 2 adjacency is established if and only if the neighbor is configured exclusively to be a Level 2 router.
Default

level-1-2

Command Mode

Interface configuration

Example

In the following example, a router is configured to require Level 1 adjacency if there is at least one area address in common between this system and its neighbors:

ip router isis interface serial 0 isis circuit-type level-1

isis csnp-interval

Use the isis csnp-interval interface configuration command to configure the IS-IS Complete Sequence Number PDUs (CSNP) interval for the specified interface. The no isis csnp-interval command restores the default value.

isis csnp-interval seconds {level-1 | level-2}
no isis csnp-interval
seconds {level-1 | level-2}
Syntax Description
seconds Interval of time between transmission of CSNPs on multiaccess networks. This interval only applies for the designated router. The default is 10 seconds.
level-1 Configures the interval of time between transmission of CSNPs for Level 1 independently.
level-2 Configures the interval of time between transmission of CSNPs for Level 2 independently.
Default

10 seconds

Command Mode

Interface configuration

Usage Guidelines

This command only applies for the designated router (DR) for a specified interface. Only DRs send CSNP packets in order to maintain database synchronization. The CSNP interval can be configured independently for Level 1 and Level 2. This feature does not apply to serial point-to-point interfaces. It does apply to WAN connections if the WAN is viewed as a multiaccess meshed network.

Example

In the following example, interface serial 0 is configured for transmitting CSN PDUs every 5 seconds. The router is configured to act as a station router.

interface serial 0 isis csnp-interval 5 level-1

isis hello-interval

Use the isis hello-interval interface configuration command to specify the length of time, in seconds, between Hello packets that the router sends on the specified interface. The no isis hello-interval command restores the default value.

isis hello-interval seconds {level-1 | level-2}
no isis hello-interval
seconds {level-1 | level-2}
Syntax Description
seconds Unsigned integer value. A value three times the Hello interval seconds is advertised as the holdtime in the Hello packets transmitted. It must be the same for all routers attached to a common network. With smaller Hello intervals, topological changes are detected faster, but there is more routing traffic. The default is 10 seconds.
level-1 Configures the Hello interval for Level 1 independently. Use this on X.25, SMDS, and Frame Relay multiaccess networks.
level-2 Configures the Hello interval for Level 2 independently. Use this on X.25, SMDS, and Frame Relay multiaccess networks.
Default

10 seconds

Command Mode

Interface configuration

Usage Guidelines

The Hello interval can be configured independently for Level 1 and Level 2, except on serial point-to-point interfaces. (Because there is only a single type of Hello packet sent on serial links, it is independent of Level 1 or Level 2.) The level-1 and level-2 keywords are used on X.25, SMDS, and Frame Relay multiaccess networks.

Example

In the following example, interface serial 0 is configured to advertise Hello packets every 5 seconds. The router is configured to act as a station router. This will cause more traffic than configuring a longer interval, but topological changes will be detected faster.

interface serial 0 isis hello-interval 5 level-1

isis metric

Use the isis metric interface configuration command to configure the metric (or cost) for the specified interface. The no isis metric command restores the default metric value.

isis metric default-metric [delay-metric [expense-metric [error-metric]]] {level-1 | level-2}
no isis metric {level-1 | level-2}
Syntax Description
default-metric Metric used for the redistributed route. The default metric is used as a value for the IS-IS metric. This is the value assigned when there is no QOS routing performed. Only this metric is supported by Cisco routers. You can configure this metric for Level 1 and/or Level 2 routing. The range is from 0 to 63. The default value is 10.
delay-metric Not supported.
expense-metric Not supported.
error-metric Not supported.
level-1 Router acts as a station router (Level 1) only.
level-2 Router acts as an area router (Level 2) only.
Default

default-metric = 10

Command Mode

Interface configuration

Usage Guidelines

Specifying the level-1 or level-2 keywords resets the metric only for Level 1 or Level 2 routing, respectively.

Example

In the following example, interface serial 0 is configured for a default link-state metric cost of 15 for Level 1:

interface serial 0 isis metric 15 level-1
Related Commands

default-information
redistribute

isis password

Use the isis password interface configuration command to configure the authentication password for a specified interface. The no isis password command disables authentication for IS-IS.

isis password password {level-1 | level-2}
no isis password {level-1 | level-2}
Syntax Description
password Authentication password you assign for an interface.
level-1 Configures the authentication password for Level 1 independently. For Level 1 routing, the router acts as a station router only.
level-2 Configures the authentication password for Level 2 independently. For Level 2 routing, the router acts as an area router only.
Default

Disabled

Command Mode

Interface configuration

Usage Guidelines

Different passwords can be assigned for different routing levels using the level-1 and level-2 keyword arguments.

Specifying the level-1 or level-2 keywords disables the password only for Level 1 or Level 2 routing, respectively. If no keyword is specified, the default is level-1.

Example

The following example configures a password for interface serial 0 at Level 1:

interface serial 0 isis password frank level-1

isis priority

Use the isis priority interface configuration command to configure the priority of designated routers. The no isis priority command resets priority to 64.

isis priority value {level-1 | level-2}
no isis priority {level-1 | level-2}
Syntax Description
value Sets the priority of a router and is a number from 0 to 127. The default value is 64.
level-1 Sets the priority of a router for Level 1 independently.
level-2 Sets the priority of a router for Level 2 independently.
Default

64

Command Mode

Interface configuration

Usage Guidelines

Priorities can be configured for Level 1 and Level 2 independently. Specifying the level-1 or
level-2 keywords resets priority only for Level 1 or Level 2 routing, respectively.

Example

The following example shows Level 1 routing given priority by setting the priority level to 50:

interface serial 0 isis priority 50 level-1

isis retransmit-interval

Use the isis retransmit-interval interface configuration command to configure the number of seconds between retransmission of IS-IS link-state PDU (LSP) retransmission for point-to-point links. The no isis retransmit-interval command restores the default value.

isis retransmit-interval seconds
no isis retransmit-interval
seconds
Syntax Description
seconds Integer that should be greater than the expected round-trip delay between any two routers on the attached network. The setting of this parameter should be conservative, or needless retransmission will result. The value should be larger for serial lines and virtual links. The default value is 5 seconds.
Default

5 seconds

Command Mode

Interface configuration

Example

The following example configures interface serial 0 for retransmission of IS-IS LSP every
10 seconds for a large serial line:

interface serial 0 isis retransmit-interval 10

keepalive

Use the keepalive interface configuration command to set the keepalive timer for a specific interface. The no keepalive command turns off keepalives entirely.

keepalive [seconds]
no keepalive [seconds]
Syntax Description
seconds (Optional.) Unsigned integer value greater than 0. The default is 10 seconds.
Default

10 seconds

Command Mode

Interface configuration

Usage Guidelines

You can configure the keepalive interval, which is the frequency at which the router sends messages to itself (Ethernet and Token Ring) or to the other end (serial), to ensure a network interface is alive. The interval in previous software versions was 10 seconds; it is now adjustable in 1-second increments down to 1 second. An interface is declared down after three update intervals have passed without receiving a keepalive packet.

Setting the keepalive timer to a low value is very useful for rapidly detecting Ethernet interface failures (transceiver cable disconnecting, cable unterminated, and so on).

A typical serial line failure involves losing Carrier Detect (CD). Since this sort of failure is typically noticed within a few milliseconds, adjusting the keepalive timer for quicker routing recovery is generally not useful.


Note When adjusting the keepalive timer for a very low bandwidth serial interface, large datagrams can delay the smaller keepalive packets long enough to cause the line protocol to go down. You may need to experiment to determine the best value.
Example

The following example sets the keepalive interval to 3 seconds:

interface ethernet 0 keepalive 3
Related Commands

A dagger (+) indicates that the command is documented in another chapter.

encapsulation ppp +
frame-relay keepalive +
smds dxi +

match

See the route-map global configuration command in this chapter.

metric holddown

Use the no metric holddown router configuration command to disable metric holddown (IGRP and RIP). Use the metric holddown command to reenable metric holddown once it is disabled.

no metric holddown
metric holddown
Syntax Description

This command has no arguments or keywords.

Default

Disabled

Command Mode

Router configuration

Usage Guidelines

Holddown keeps new routing information from being used for a certain period of time. This can prevent routing loops caused by slow convergence. It is sometimes advantageous to disable holddown to increase the network's ability to quickly respond to topology changes; this command provides this function.

This command assumes that the entire AS is running Cisco Version 8.2(5) or more recent software since the hop count is used to avoid information looping. Using it with earlier software will cause inconsistent routing behavior.

Example

The following example disables metric holddown:

router igrp 15 network 131.108.0.0 network 192.31.7.0 no metric holddown
Related Commands

metric weights
metric maximum-hops
timers basic

metric maximum-hops

Use the metric maximum-hops router configuration command to cause the IP routing software to advertise as unreachable those routes with a hop count higher than is specified by the command (IGRP only). Use the no metric maximum-hops command to reset the value to the default.

metric maximum-hops hops
no metric maximum-hops hops
Syntax Description
hops Maximum hop count (in decimal). The default value is 100 hops; the maximum number of hops that can be specified is 255.
Default

100 hops

Command Mode

Router configuration

Usage Guidelines

This command provides a safety mechanism that breaks any potential count-to-infinity problems. It causes the IP routing software to advertise as unreachable routes with a hop count greater than the value assigned to the hops argument.

Example

In the following example, a router in AS 71 attached to network 15.0.0.0 wants a maximum hop count of 200, doubling the default. The network administrators decided to do this because they have a complex WAN that can generate a large hop count under normal (nonlooping) operations.

router igrp 71 network 15.0.0.0 metric maximum-hops 200
Related Commands

metric weights
metric holddown

metric weights

Use the metric weights router configuration command to allow the tuning of the IGRP metric calculations. Use the no metric weights command to reset the values to their defaults.

metric weights TOS K1 K2 K3 K4 K5
no metric weights
Syntax Description
TOS Type of Service. Currently it must always be zero.
K1-K5 Constants that convert an IGRP metric vector into a scalar quantity.
Default

The default version of IGRP is K1 = K3 = 1, K2 = K4 = K5 = 0.

Command Mode

Router configuration

Usage Guidelines

Use this command to alter the default behavior of IGRP routing and metric computation and allow the tuning of the IGRP metric calculation for a particular Type of Service (TOS).

If K5 equals 0, the composite IGRP metric is computed according to the following formula:

metric = [K1 * bandwidth + (K2 * bandwidth)/(256 - load) + K3 * delay]

If K5 does not equal zero, an additional operation is done:

metric = metric * [K5 / (reliability + K4)]

Bandwidth is inverse minimum bandwidth of the path in bits per second scaled by a factor of 10*1010. The range is from a 1200 bps line to 10 Gbps.

Delay is in units of 10 microseconds. This gives a range of 10 microseconds to 168 seconds. A delay of all ones indicates that the network is unreachable.

The delay parameter is stored in a 24-bit field, in tens of microseconds. Hence, the delay can be from 1 (10 microseconds) to hex FFFFFF (decimal 16777215), which corresponds to 167.77215 seconds. A delay of all ones (that is, a delay of 16777215) indicates that the network is unreachable.

Table 1-2 lists the default values used for several common media.


Bandwidth Values By Media Type
Media Type Delay Bandwidth
Satellite 200,000 (2 sec) 20 (500 Mbit)
Ethernet 100 (1 ms) 1,000
1.544 Mbps 2000 (20 ms) 6,476
64 kbps 2000 156,250
56 kbps 2000 178,571
10 kbps 2000 1,000,000
1 kbps 2000 10,000,000

Reliability is given as a fraction of 255. That is, 255 is 100 percent reliability or a perfectly stable link.

Load is given as a fraction of 255. A load of 255 indicates a completely saturated link.

Example

The following example sets the metric weights to slightly different values than the defaults.

router igrp 109 network 131.108.0.0 metric weights 0 2 0 2 0 0
Related Commands

A dagger (+) indicates that the command is documented in another chapter.

bandwidth +
delay +
metric holddown
metric maximum-hops

neighbor (EGP, BGP, IGRP, RIP)

Use the neighbor router configuration command to define a neighboring router with which to exchange routing information. Use the no neighbor command to remove an entry.

neighbor ip-address
no neighbor ip-address
Syntax Description
ip-address IP address of a peer router with which routing information will be exchanged.
Default

None

Command Mode

Router configuration

Usage Guidelines

For exterior routing protocols such as EGP and BGP, this command specifies routing peers. For normally broadcast protocols such as IGRP or RIP, this command permits the point-to-point (nonbroadcast) exchange of routing information. When used in combination with the passive-interface router configuration command, routing information can be exchanged between a subset of routers on a LAN.

Multiple neighbor commands can be used to specify additional neighbors or peers.

OSPF has its own version of the neighbor command. See the neighbor (OSPF) command page in this chapter.

Examples

The following example establishes an EGP neighbor:

autonomous system 109 router egp 110 neighbor 131.108.1.1

In the following example, IGRP updates are sent to all interfaces on network 131.108.0.0 except interface Ethernet 1. However, in this case a neighbor router configuration command is included. This command permits the sending of routing updates to specific neighbors. One copy of the routing update is generated per neighbor.

router igrp 109 network 131.108.0.0 passive-interface ethernet 1 neighbor 131.108.20.4
Related Command

passive-interface

neighbor (OSPF)

Use this form of the neighbor router configuration command to configure OSPF routers interconnecting to nonbroadcast networks. Use the no form of this command with the appropriate IP address and arguments to remove the configuration.

neighbor ip-address [priority number] [poll-interval number-of-seconds]
no neighbor
ip-address [priority number] [poll-interval number-of-seconds]
Syntax Description
ip-address Interface IP address of the neighbor.
priority number (Optional.) 8-bit number indicating the router priority value of the nonbroadcast neighbor associated with the IP address specified. The default is 0.
poll-interval number-of- seconds (Optional.) Unsigned integer value reflecting the poll interval. RFC 1247 recommends that this value should be much larger than the Hello interval. The default is 2 minutes (120 seconds).
Default

Disabled

Command Mode

Router configuration

Usage Guidelines

X.25 and Frame Relay provide an optional broadcast capability that can be configured in the map to allow OSPF to run as a broadcast network. At the OSPF level you can configure the router as a broadcast network. See the x25 map and frame-relay map interface configuration command descriptions in Chapters 7 and 8, respectively, of this manual for more detail.

One neighbor entry must be included in the router's configuration for each known nonbroadcast network neighbor. The neighbor address has to be on the primary address of the interface.

If a neighboring router has become inactive (Hello packets have not been seen for the Router DeadInterval period), it may still be necessary to send Hello packets to the dead neighbor. These Hello packets will be sent at a reduced rate called Poll Interval.

When the router first starts up, it sends only Hello packets to those routers with non-zero priority, that is, routers which are eligible to become designated routers (DR) and back-up designated routers (BDR). After DR and BDR are selected, DR and BDR will then start sending Hello packets to all neighbors in order to form adjacencies.

Example

The following example declares a router at address 131.108.3.4 on a nonbroadcast network, with a priority of 1 and a poll-interval of 180:

router ospf neighbor 131.108.3.4 priority 1 poll-interval 180
Related Command

ip ospf priority

neighbor (configure-neighbors)

Use this form of the neighbor router configuration command to instruct the router to treat temporary neighbors which have been accepted by a template as if they had been configured by hand. The no form of the command causes any new neighbor accepted by the template to be treated as temporary.

neighbor template-name configure-neighbors
no neighbor
template-name configure-neighbors
Syntax Description
template-name A user selectable designation that identifies a particular template (an arbitrary word).
Default

Disabled

Command Mode

Router configuration

Usage Guidelines

Under normal circumstances, neighbors that are allowed to connect to the router because you had configured a template are treated as temporary. When a temporary neighbor disconnects, the local router will not try to actively reestablish a connection with it. In addition, information about temporary neighbors will not show up in the router configuration (write terminal).

When configure-neighbors is enabled on a particular template, any neighbor accepted by that template will be treated as if it had been manually configured. These neighbors will show up in write terminal displays and will be written to the non-volatile configuration if a write memory command is issued.

Example

In the following example, any BGP speaker matching access-list 7 can connect to the router and exchange information. Any neighbor who connects will be treated as if it had been manually configured.

access-list 7 permit 168.89.3.0 0.0.0.255 neighbor internal-ethernet neighbor-list 7 neighbor internal-ethernet configure-neighbors
Related Command

neighbor (neighbor-list)

neighbor (distribute-list)

Use this form of the neighbor router configuration command to distribute BGP neighbor information as specified in an access list. Use the no form of this command to remove an entry.

neighbor ip-address distribute-list access-list-number {in | out}
no neighbor ip-address distribute-list access-list-number {in | out}
Syntax Description
ip-address Neighbor's IP address.
access-list-number Predefined access list number. Only standard access lists can be used with this command.
in Access list is applied to incoming advertisements to that neighbor.
out Access list is applied to outgoing advertisements from that neighbor.
Default

Disabled

Command Mode

Router configuration

Usage Guidelines

Using distribute lists is one of two ways to filter BGP advertisements. The other way is to use AS-path filters, as with the ip as-path access-list global configuration command and the neighbor filter-list command.

Example

The following example applies list 39 to incoming advertisements to neighbor 120.23.4.1:

router bgp 109 network 131.108.0.0 neighbor 120.23.4.1 distribute-list 39 in
Related Commands

ip as-path access-list
neighbor
(filter-list)

neighbor (ebgp-multihop)

Use this form of the neighbor router configuration command to accept and attempt BGP connections to external peers residing on networks that are not directly connected. Use the no form of the command to return to the default of allowing only directly connected neighbors.

neighbor ip-address ebgp-multihop
no neighbor ip-address
Syntax Description
ip-address IP address of the BGP-speaking neighbor.
ebgp-multihop Allow connections to or from external BGP neighbors residing on networks not directly connected to the router.
Default

None

Command Mode

Router configuration

Usage Guidelines

This feature should only be used under the guidance of technical support staff.

Example

The following example allows connections to or from neighbor 131.108.1.1:

router bgp 109 neighbor 131.108.1.1 ebgp-multihop

neighbor (filter-list)

Use this form of the neighbor router configuration command to set up BGP filters, using access lists defined with the ip as-path access-list command. Use the no form of this command to disable this function.

neighbor ip-address filter-list access-list-number {in | out | weight weight}
no neighbor ip-address filter-list access-list-number {in | out | weight weight}
Syntax Description
ip-address IP address of the neighbor.
access-list-number Predefined AS path access list number.
in Access list to incoming routes.
out Access list to outgoing routes.
weight weight Assigns a relative importance to incoming routes matching AS paths. Acceptable values are -65536 to 65535.
Default

Disabled

Command Mode

Router configuration

Usage Guidelines

This command establishes filters on both inbound and outbound BGP routes. If a weight is assigned, the given weight is added to the weight of the router if the AS path matches the regular expression. Any number of weight filters are allowed on a per-neighbor basis, but only one in or out filter is allowed. The weight of a route affects BGP's route-selection rules.

See the "Regular Expressions" appendix for information on forming regular expressions.

Example

In the following example, the BGP neighbor with IP address 128.125.1.1 is not sent advertisements about any path through or from the adjacent AS 123.

ip as-path access-list 1 deny ^123$ ip as-path access-list 1 deny ^123 .* ! The space in the above expression (^123 .*)is required. router bgp 109 network 131.108.0.0 neighbor 129.140.6.6 remote-as 123 neighbor 128.125.1.1 remote-as 47 neighbor 128.125.1.1 filter-list 1 out
Related Commands

ip as-path access-list
neighbor
(distribute-list)
neighbor (weight)

neighbor (neighbor-list)

Use this form of the neighbor router configuration command to configure BGP to support anonymous neighbor peerings by configuring a neighbor template. Use the no form of this command to delete the template, and also cause any temporary neighbors accepted by the template to be shut down and removed.

neighbor template-name neighbor-list access-list-number
no neighbor template-name neighbor-list
Syntax Description
template-name A user selectable designation that identifies a particular template (an arbitrary word).
access-list-number An IP access list number in the range 1-99.
Default

Disabled

Command Mode

Router configuration

Usage Guidelines

To specify a group of anonymous neighbors, configure a neighbor template rather than specifically configure each neighbor. The template allows you to specify an IP access list which defines remote systems that can establish a BGP connection to the router. External BGP peers must be on a directly connected Ethernet unless they are overridden by the neighbor ebgp-multihop command.

Once you specify a template, you configure the template as if it were a regular neighbor entry, such as setting the protocol version or filter lists, so that anonymous neighbors accepted by the template will receive the settings of the template.

These neighbors accepted by the template appear in the show ip bgp summary and show ip bgp neighbor displays, although they do not appear in the router configuration. When the session is disconnected, all knowledge about the neighbor is discarded and the router will not attempt to actively re-establish a connection.

You can use the neighbor configure-neighbors command to request that the router treat peers learned through a template as if they were manually configured neighbors. These peers will then show up in write terminal displays and can be stored as part of the non-volatile configuration.

Examples

In the following example, any BGP speaker from 168.89.3.0 can connect to the router and exchange information:

access-list 7 permit 168.89.3.0 0.0.0.255 neighbor internal-ethernet neighbor-list 7 neighbor internal-ethernet configure-neighbors

In the following example, any BGP speaker in the connected internet can establish a BGP connection to the local router, and the local router will send them routing information. However, the distribute-list clause instructs the local router to ignore all information these remote BGP speakers send to it.

access-list 9 permit 0.0.0.0 255.255.255.255 access-list 10 deny 0.0.0.0 255.255.255.255 neighbor route-server-peers neighbor-list 9 neighbor route-server-peers distribute-list 10 in
Related Commands

access-list (standard)
neighbor (configure-neighbors)
neighbor (ebgp-multihop)

neighbor (next-hop-self)

Use this form of the neighbor router configuration command to configure the router to disable next-hop processing on BGP updates. Use the no neighbor next-hop-self command to return to the default.

neighbor ip-address next-hop-self
no neighbor ip-address next-hop-self
Syntax Description
ip-address IP address of the BGP-speaking neighbor.
next-hop-self Advertise local router as next hop.
Default

None

Command Mode

Router configuration

Usage Guidelines

This is useful in non-meshed networks such as Frame Relay or X.25 where BGP neighbors may not have direct access to all other neighbors on the same IP subnet.

Example

The following example forces all updates destined for 131.108.1.1 to advertise this router as the next hop:

router bgp 109 neighbor 131.108.1.1 next-hop-self

neighbor (remote-as)

Use this form of the neighbor router configuration command to add an entry to the BGP neighbor table. Use the no form of this command to remove a neighbor.

neighbor ip-address remote-as number
no neighbor ip-address remote-as number
Syntax Description
ip-address Neighbor's IP address.
number AS to which the neighbor belongs.
Default

Disabled

Command Mode

Router configuration

Usage Guidelines

Specifying a neighbor with an AS number that matches the AS number specified in the router bgp global configuration command identifies the neighbor as internal to the local AS. Otherwise, the neighbor is considered external.

Examples

The following example specifies that the router at the address 131.108.1.2 is a neighbor in AS number 109:

router bgp 110 network 131.108.0.0 neighbor 131.108.1.2 remote-as 109

In the following example, a BGP router is assigned to AS 109, and two networks are listed as originating in the AS. Then the addresses of three remote routers (and their ASs) are listed. The router being configured will share information about networks 131.108.0.0 and 192.31.7.0 with the neighbor routers. The first router listed is in the same Class B network address space, but in a different AS; the second neighbor command illustrates specification of an internal neighbor (with the same AS number) at address 131.108.234.2; and the last neighbor command specifies a neighbor on a different network.

router bgp 109 network 131.108.0.0 network 192.31.7.0 neighbor 131.108.200.1 remote-as 167 neighbor 131.108.234.2 remote-as 109 neighbor 150.136.64.19 remote-as 99

neighbor (third-party)

Use this form of the neighbor router configuration command to send updates regarding EGP third-party routers. Use the no form of this command to disable these updates.

neighbor ip-address third-party third-party-ip-address [internal | external]
no neighbor ip-address third-party third-party-ip-address [internal | external]
Syntax Description
ip-address IP address of the EGP peer.
third-party-ip-address Address of the third-party router on the network shared by the Cisco router and the EGP peer specified by address.
internal (Optional.) Indicates that the third-party router should be listed in the internal section of the EGP update. This is the default.
external (Optional.) Indicates that the third-party router should be listed in the external section of the EGP update.
Default

Disabled

Command Mode

Router configuration

Usage Guidelines

Using this third-party mechanism, EGP tells its peer that another router (the third party) on the shared network is the appropriate router for some set of destinations. If updates mentioning third-party routers are desired, use this command.

All networks reachable through the third-party router will be listed in the EGP updates as reachable by the router. The optional internal and external keywords indicate whether the third-party router should be listed in the internal or external section of the EGP update. Normally, all networks are mentioned in the internal section.

This command can be used multiple times to specify additional third-party routers.

Examples

In the following example, routes learned from router 131.108.6.99 will be advertised to 131.108.6.5 as third-party internal routes:

neighbor 131.108.6.5 third-party 131.108.6.99 internal

In the following example, routes learned from 131.108.6.100 will be advertised to 131.108.6.5 as third-party external routes:

neighbor 131.108.6.5 third-party 131.108.6.100 external

neighbor (update-source)

Use this form of the neighbor router configuration command to configure the router to allow internal BGP sessions to use any operational interface for TCP connections. The no form of this command restores the interface assignment to the closest interface, also called the best-local-address.

neighbor ip-address update-source interface
no neighbor
ip-address update-source interface
Syntax Description
ip-address IP address of the BGP-speaking neighbor.
interface Loopback interface.
Default

best-local-address

Command Mode

Router configuration

Usage Guidelines

This feature works in conjunction with the Loopback interface feature described in Chapter 6 of the Router Products Configuration Guide.

Example

In the following example, BGP TCP connections for the specified neighbor(s) will be sourced with Loopback interface's IP address rather than the best-local-address:

router bgp 110 network 160.89.0.0 neighbor 160.89.2.3 remote-as 110 neighbor 160.89.2.3 update-source Loopback0

neighbor (version)

Use this form of the neighbor router configuration command to configure the router to accept only Version 2 of the BGP protocol and permit dynamic version negotiation with neighbors. The no form of this command returns the version to the default level of that neighbor.

neighbor ip-address version value
no neighbor
ip-address version value
Syntax Description
ip-address IP address of the BGP-speaking neighbor.
version value Version number. The version can be set to 2 to force the router to only use Version 2 with the specified neighbor. The default is to use Version 3 of BGP and dynamically negotiate down to Version 2 if requested.
Default

Version 3

Command Mode

Router configuration

Usage Guidelines

Our implementation of BGP supports Versions 2 and 3 of the protocol and permits dynamic version negotiation with neighbors.

Example

The following example locks down to Version 2 of the BGP protocol:

router bgp 109 neighbor 131.104.27.2 version 2

neighbor (weight)

Use this form of the neighbor router configuration command to specify a weight to assign to a specific neighbor connection. The no form of this command removes the assignment.

neighbor ip-address weight weight
no neighbor
ip-address weight weight
Syntax Description
ip-address Neighbor's IP address.
weight weight Weight to assign. Acceptable values are -65536 to 65535.
Default

Routes learned through another BGP peer have a default weight of 0 and routes sourced by the local router have a default weight of 32768.

Command Mode

Router configuration

Usage Guidelines

All routes learned from this neighbor will have the assigned weight initially. The route with the highest weight will be chosen as the preferred route when multiple routes are available to a particular network.


Note For weight changes to take effect, it may be necessary to use clear ip bgp *.
Example

The following example increases by 50 the weight of all routes learned via 151.23.12.1:

router bgp 109 neighbor 151.23.12.1 weight 50 neighbor 151.23.12.1 filter-list 1 weight 10
Related Commands

neighbor (distribute-list)
neighbor (filter-list)

neighbor any

Use the neighbor any router configuration command to control how neighbor entries are added to the routing table for both EGP and BGP. The no neighbor any command removes the configuration.

neighbor any [access-list-number]
no neighbor any [
access-list-number]
Syntax Description
access-list-number (Optional.) Access list number the neighbor must be accepted by to be allowed to peer with the EGP or BGP process. If no list is specified, any neighbor will be allowed to peer with the router.
Default

Disabled

Command Mode

Router configuration

Example

The following example configuration illustrates the use of the neighbor any command in conjunction with the access-list global configuration command:

access-list 1 permit 10.0.0.0 0.255.255.255 ! global access list assignment router egp 0 neighbor any 1
Related Commands

A dagger (+) indicates that the command is documented in another chapter.

access-list +
neighbor any third-party
router egp 0

neighbor any third-party

Use the neighbor any third-party router configuration command to configure an EGP process that determine which neighbors will be treated as the next hop in EGP advertisements. The no neighbor any third-party command removes the configuration.

neighbor any third-party ip-address [internal | external]
no neighbor any third-party
ip-address [internal | external]
Syntax Description
ip-address IP address of the third-party router that is to be the next hop in EGP advertisements.
internal (Optional.) Indicates that the third-party router should be listed in the internal section of the EGP update.
external (Optional.) Indicates that the third-party router should be listed in the external section of the EGP update.
Default

Disabled

Command Mode

Router configuration

Example

The following example illustrates how to specify the particular neighbors that an EGP process will view as peers:

access-list 2 permit 10.0.0.0 0.255.255.255 ! global access list assignment router egp 0 neighbor any 2 neighbor any third-party 10.1.1.1
Related Commands

neighbor any
router egp 0

net

Use the net router configuration command to configure a Network Entity Title (NET) for the routing process. The no net command removes a specific NET; you must specify the NET.

net network-entity-title
no net network-entity-title
Syntax Description
network-entity-title NET that specifies the area address and the system ID for an IS-IS routing process. This argument can be either an address or a name.
Default

None

Command Mode

Router configuration

Usage Guidelines

For IS-IS, multiple NETs per router are allowed, with a maximum of three. There is no default value for this command.

Example

The following example illustrates specifying a single NET:

router isis Pieinthesky net 47.0004.004d.0001.0000.0c11.1111.00

network (BGP)

Use the network router configuration command to specify the BGP network to be advertised as originating within the current AS. The no network command removes the specified network.

network network-number
no network
network-number
Syntax Description
network-number IP address of the network.
Default

Disabled

Command Mode

Router configuration

Usage Guidelines

These types of networks can be learned from connected routes, dynamic routing, and from static route sources.

A maximum of 200 network commands may be specified for a single BGP process.

Example

The following example sets up network 131.108.0.0 to be included in the router's BGP updates:

router bgp 120 network 131.108.0.0
Related Command

router bgp

network (backdoor)

Use this form of the network router configuration command to specify a backdoor route to a BGP border router that will provide better information about the network. The no form of this command removes an address from the list.

network address backdoor
no network address backdoor
Syntax Description
address IP address of the network to which you want a backdoor route.
Default

Disabled

Command Mode

Router configuration

Usage Guidelines

A backdoor network is treated as a local network, except that it is not advertised.

Example

The following example configures network 131.108.0.0 as a local network and network 192.31.7.0 as a backdoor network:

router bgp 109 network 131.108.0.0 network 192.31.7.0 backdoor

network (EGP)

Use the network router configuration command to specify the list of networks for the EGP routing process. The no network command removes a network from the list.

network network-number
no network
network-number
Syntax Description
network-number IP address of a peer router with which routing information will be exchanged.
Default

Disabled

Command Mode

Router configuration

Usage Guidelines

The networks to be advertised to the EGP peers of an EGP routing process are advertised with a distance of zero. The restrictions on the network you specify are that it must appear in the routing table, and the network number must not contain any subnet information. The network can be connected, statically configured, or redistributed into EGP from other routing protocols. Multiple commands can be used to specify additional networks.

Example

The following example illustrates a typical configuration for an EGP router process. The router is in autonomous system 109 and is peering with routers in AS 164. It will advertise the networks 131.108.0.0 and 192.31.7.0 to the router in AS 164, 10.2.0.2. The information sent and received from peer routers can be filtered in various ways, including blocking information from certain routers and suppressing the advertisement of specific routes.

autonomous-system 109 router egp 164 network 131.108.0.0 network 192.31.7.0 neighbor 10.2.0.2
Related Command

router egp

network (IGRP)

Use the network router configuration command to specify a list of networks for the IGRP routing process. The no network command removes a network from the list.

network network-number
no network
network-number
Syntax Description
network-number IP address of the directly connected network.
Default

Disabled

Command Mode

Router configuration

Usage Guidelines

The network number specified must not contain any subnet information. You can specify multiple network commands.

IGRP sends updates to the interfaces in the specified network(s). Also, if an interface's network is not specified, it will not be advertised in any IGRP update.

Example

The following example configures a router for IGRP and assigns AS 109. The network commands indicate the networks directly connected to the router.

router igrp 109 network 131.108.0.0 network 192.31.7.0
Related Command

router igrp

network (OSPF)

Use this form of the network router configuration command to define the interfaces on which OSPF runs and to define the area ID for those interfaces. The no form of this command disables OSPF routing for interfaces defined with the address wildcard-mask pair; you must specify the complete address range and area ID.

network address wildcard-mask area area-id
no network
address wildcard-mask area area-id
Syntax Description
address IP address.
wildcard-mask IP-address-type mask that includes "don't care" bits.
area-id Area that is to be associated with the OSPF address range. It can be specified as either a decimal value or as an IP address. If you intend to associate areas with IP subnets, you can specify a subnet address as the area-id.
Default

Disabled

Command Mode

Router configuration

Usage Guidelines

The address and wildcard-mask arguments together allow you to define one or multiple interfaces to be associated with a specific OSPF area using a single command. Using the wildcard-mask allows you to define one or multiple interfaces to be associated with a specific OSPF area using a single command. If you intend to associate areas with IP subnets, you can specify a subnet address as the area-id.


Note Any individual interface can only be attached to a single area. If the address ranges specified for different areas overlap, the router will adopt the first area in the network command list and ignore the subsequent overlapping portions. In general, it is recommended that you devise address ranges that do not overlap in order to avoid inadvertent conflicts.
Example

In the following partial example, OSPF routing process 109 is initialized, and four OSPF areas are defined: 10.9.50.0, 2, 3, and 0. Areas 10.9.50.0, 2, and 3 mask specific address ranges, while Area 0 enables OSPF for all other networks.

router ospf 109 network 131.108.20.0 0.0.0.255 area 10.9.50.0 network 131.108.0.0 0.0.255.255 area 2 network 131.109.10.0 0.0.0.255 area 3 network 0.0.0.0 255.255.255.255 area 0
Related Command

router ospf

network (RIP)

Use the network router configuration command to specify a list of networks for the RIP routing process. The no network command removes a network from the list.

network network-number
no network
network-number
Syntax Description
network-number IP address of the network of directly connected networks.
Default

Disabled

Command Mode

Router configuration

Usage Guidelines

The network number specified must not contain any subnet information. You can specify multiple network commands. RIP routing updates will be sent and received only through interfaces on this network.

RIP sends updates to the interfaces in the specified network(s). Also, if an interface's network is not specified, it will not be advertised in any RIP update.

Example

The following example defines RIP as the routing protocol to be used on all interfaces connected to networks 128.99.0.0 and 192.31.7.0:

router rip network 128.99.0.0 network 192.31.7.0
Related Command

router rip

offset-list

Use the offset-list router configuration command to add or remove a positive offset to incoming and outgoing metrics for networks matching a specified access list (for IGRP and RIP only). The no offset-list command with the appropriate keywords removes the offset list.

offset-list {in | out} offset [access-list-number]
no offset-list {in | out} offset [access-list-number]
Syntax Description
in Applies the access list to incoming metrics.
out Applies the access list to outgoing metrics.
offset Positive offset to be applied to metrics for networks matching the access list. If the offset is zero, no action is taken.
access-list-number (Optional.) Access list to be applied. If unspecified, the argument supplied to offset is applied to all metrics. If offset is zero, no action is taken. For IGRP, the offset is added to the delay component only. Must be a standard access list.
Default

Disabled

Command Mode

Router configuration

Example

The following example for a router using IGRP applies an offset of 10 to its delay component for all outgoing metrics:

offset-list out 10

passive-interface

Use the passive-interface router configuration command to disable sending routing updates on an interface. The no passive-interface command reenables sending routing updates on the specified interface.

passive-interface interface
no passive-interface interface
Syntax Description
interface Specified interface. The particular subnet will continue to be advertised to other interfaces. Updates from other routers on that interface continue to be received and processed.
Default

Disabled

Command Mode

Router configuration

Usage Guidelines

For OSPF, OSPF routing information is neither sent nor received through the specified router interface. The specified interface address appears as a stub network in the OSPF domain.

For IS-IS, this command instructs IS-IS to advertise the IP addresses for the specified interface without actually running IS-IS on that interface. The no form of this command for IS-IS disables advertising IP addresses for the specified address.

Example

The following example sends IGRP updates to all interfaces on network 131.108.0.0 except interface Ethernet 1:

router igrp 109 network 131.108.0.0 passive-interface ethernet 1

The following configuration enables IS-IS on interfaces Ethernet 1 and serial 0 and advertises the IP addresses of Ethernet 0 in its Link State PDUs:

router isis Finance passive interface Ethernet 0 interface Ethernet 1 ip router isis Finance interface serial 0 ip router isis Finance

redistribute

Use the redistribute router configuration command to redistribute routes from one routing domain into another routing domain. The no form of this command ends redistribution of information when you supply the appropriate arguments, or disables any of the specified keywords.

redistribute protocol [process-id] {level-1 | level-1-2 | level-2} [metric metric-value]
[metric-type type-value] [match internal | external 1 | external 2]
[
tag tag-value] [route-map map-tag] [weight weight] [subnets]

no redistribute protocol [process-id] {level-1 | level-1-2 | level-2} [metric metric-value]
[metric-type type-value] [match internal | external 1 | external 2]
[tag tag-value] [route-map map-tag] [weight weight] [subnets]
Syntax Description
protocol The source protocol from which routes are being redistributed. It can be one of the following keywords: bgp, egp, igrp, isis, ospf, static [ip], connected and rip.

The keyword static [ip] is used to redistribute IP static routes. The optional ip keyword is used when redistributing into IS-IS.

The keyword connected refers to routes which are established automatically by virtue of having enabled IP on an interface. For routing protocols such as OSPF and IS-IS, these routes will be redistributed as external to the AS.

process-id For bgp, egp, or igrp, this is an Autonomous System (AS) number, a 16-bit decimal number.
For isis, this is an optional tag that defines a meaningful name for a routing process. You can specify only one IS-IS process per router. Creating a name for a routing process means that you use names when configuring routing.
For ospf, this is an appropriate OSPF process ID from which routes are to be redistributed. This identifies the routing process. This value takes the form of a nonzero decimal number.
For rip, no process-id value is needed.
level-1 For IS-IS, Level 1 routes are redistributed into other IP routing protocols independently.
level-1-2 For IS-IS, both Level 1 and Level 2 routes are redistributed into other IP routing protocols.
level-2 For IS-IS, Level 2 routes are redistributed into other IP routing protocols independently.
metric metric-value (Optional.) Metric used for the redistributed route. If a value is not specified for this option, and no value is specified using the default-metric router configuration command, the default metric value is 0. Use a value consistent with the destination protocol.
metric-type type-value (Optional.) For OSPF, the external link type associated with the default route advertised into the OSPF routing domain. It can be one of two values:

1--Type 1 external route

2--Type 2 external route

If a metric-type is not specified, the router adopts a Type 2 external route.

For IS-IS, it can be one of two values:

internal--IS-IS metric which is < 63.

external--IS-IS metric which is > 64 < 128.

The default is internal.

match internal | external (Optional.) For OSPF, the criteria by which OSPF routes are redistributed into other routing domains. It can be one of the following:

internal: Routes that are internal to a specific AS.

external 1: Routes that are external to the AS, but are imported into OSPF as Type 1 external routes.

external 2: Routes that are external to the AS, but are imported into OSPF as Type 2 external routes.

external type-value (Optional.) External route type to be redistributed into other routing domains:

1--Type 1 external route

2--Type 2 external route

The default is internal.

tag tag-value (Optional.) 32-bit decimal value attached to each external route. This is not used by the OSPF protocol itself. It may be used to communicate information between AS boundary routers. If none is specified, then the remote AS number is used for routes from BGP and EGP; for other protocols, zero (0) is used.
route-map (Optional.) Route map should be interrogated to filter the importation of routes from this source routing protocol to the current routing protocol. If not specified, all routes are redistributed. If this keyword is specified, but no route map tags are listed, no routes will be imported.
map-tag Identifier of a configured route map.
subnets (Optional.) For redistributing routes into OSPF, the scope of redistribution for the specified protocol.

Default

See "Syntax Description" for the various defaults.

Command Mode

Router configuration

Usage Guidelines

Changing or disabling any keyword will not affect the state of other keywords.

A router receiving a link-state protocol (LSP) with an internal metric will consider the cost of the route from itself to the redistributing router plus the advertised cost to reach the destination. An external metric only considers the advertised metric to reach the destination.

Routes learned from IP routing protocols can be redistributed at level-1 into an attached area or at level-2. The keyword level-1-2 allows both in a single command.

Redistributed routing information should always be filtered by the distribute-list out router configuration command. This ensures that only those routes intended by the administrator are passed along to the receiving routing protocol.

Whenever you use the redistribute or the default-information router configuration commands to redistribute routes into an OSPF routing domain, the router automatically becomes an AS boundary router. However, an AS boundary router does not, by default, generate a default route into the OSPF routing domain.

When routes are redistributed between OSPF processes, no OSPF metrics are preserved.

The only connected routes affected by this redistribute command are the routes not specified by the network command.

You cannot use the default-metric command to affect the metric used to advertise connected routes.

When routes are redistributed into OSPF and metric is omitted, OSPF uses the default metric of 20 for routes from all protocols except BGP routes, which have a metric of 1.


Note The metric value specified in the redistribute command supersedes the metric value specified using the default-metric command.
Examples

The following are examples of the various configurations you would use to redistribute one routing protocol into another routing protocol.

The following example configuration causes OSPF routes to be redistributed into a BGP domain:

router bgp 109 redistribute ospf...

The following example configuration causes IGRP routes to be redistributed into an OSPF domain:

router ospf 110 redistribute igrp...

The following example illustrates the use of this form of the redistribute command, with the match keyword and its options enabled:

router igrp 108 redistribute ospf 109 match internal external 1 external 2

The following example causes the specified IGRP process routes to be redistributed into an OSPF domain. The IGRP-derived metric will be remapped to 100 and RIP routes to 200.

router ospf 109 redistribute igrp 108 metric 100 subnets redistribute rip metric 200 subnets

In the following example, BGP routes are configured to be redistributed into IS-IS. The link-state cost is specified as 5, and the metric type will be set to external, indicating that it has lower priority than internal metrics.

router isis redistribute bgp 120 metric 5 metric-type external
Related Commands

default-information originate
distribute-list out
route-map
show route-map

route-map (including match and set route-map configuration commands)

Use the route-map global configuration command, and the route-map configuration commands match and set, to define the conditions for redistributing routes from one routing protocol into another. Each route-map command has a list of match and set commands associated with it. The match commands specify the match criteria-- the conditions under which redistribution is allowed for the current route-map. The set commands specify the set actions--the particular redistribution actions to perform if the criteria enforced by the match commands are met. The no route-map command deletes the route map.

route-map map-tag {permit | deny} sequence-number
no route-map map-tag {permit | deny} sequence-number
Syntax Description
map-tag Defines a meaningful name for the route map. The redistribute router configuration command uses this name to reference this route map. Multiple route maps may share the same map tag name.
permit If the match criteria are met for this route map, and permit is specified, the route is redistributed as controlled by the set actions. If the match criteria are not met, and permit is specified, the next route map with the same map-tag is tested. If a route passes none of the match criteria for the set of route maps sharing the same name, it is not redistributed by that set.
deny If the match criteria are met for the route map, and deny is specified, the route is not redistributed, and no further route maps sharing the same map tag name will be examined.
sequence-number Number that indicates the position a new route map is to have in the list of route maps already configured with the same name. If given with the no form of this command, it specifies the position of the route map that should be deleted.

match route-map configuration commands

The match route-map configuration command has multiple formats. Each format is shown below, described as separate commands. The match commands may be given in any order, and all match commands must "pass" to cause the route to be redistributed according to the set actions given with the set commands. The no forms of the match commands remove the specified match criteria.

Use this form of the match command for any routes with address specified by a standard access list:

match ip address access-list-number [access-list-number...access-list-number]
no match ip address access-list
-number [access-list-number...access-list-number]
Syntax Description
ip address Any routes with the network address passed by one or more of the standard access lists specified will be redistributed.
access-list-number One or more numeric identifiers of access lists.

The access list number must be the number of a standard access list; that is, it must be a number from 1 through 99. Also, the access list that you specify must have a nonzero mask. If the mask is 0.0.0.0, the command will not match any route to the specified network for the route map. The following is an example of how to specify the access-list command:

access-list 30 permit 131.108.0.0 0.0.255.255

The following are incorrect ways of specify the preceding access-list command. This first command is incorrect because no mask is specified. The second command is incorrect because the mask is all zeros.

access-list 30 permit 131.108.0.0 access-list 30 permit 131.108.0.0 0.0.0.0

Use this form of the match command for any routes which have their next hop out one of the interfaces specified:

match interface name unit [name unit...name unit]
no match interface name unit [name unit...name unit]
Syntax Description
interface Any routes which have their next hop out one of the interfaces specified will be redistributed.
name unit Names of interfaces, such as Ethernet 0 or Serial 2.

Use this form of the match command for any routes with the metric specified:

match metric metric-value
no match metric metric-value
Syntax Description
metric Any routes with the metric specified will be redistributed.
metric-value Route metric. This may be an IGRP five-part metric.

Use this form of the match command for any routes which have a next-hop router address passed by one of the access lists specified:

match ip next-hop access-list-number [access-list-number...access-list-number]
no match ip next-hop
access-list-number [access-list-number...access-list-number]
Syntax Description
next-hop Any routes which have a next-hop router address passed by one of the access lists specified will be redistributed.
access-list-number One or more numeric identifiers of standard access lists.

Use this form of the match command for any routes which have been advertised by routers at the address specified by the access lists:

match ip route-source access-list-number [access-list-number...access-list-number]
no match ip route-source
access-list-number [access-list-number...access-list-number]
Syntax Description
route-source Any routes which have been advertised by routers at the address specified by the access lists will be redistributed. There are situations in which a route's next hop and source router address may not be the same.
access-list-number One or more numeric identifiers of access lists.

Use this form of the match command for any routes which are of the specified type:

match route-type {internal | external | level-1 | level-2}
no match route-type {internal | external | level-1 | level-2}
Syntax Description
route-type Any routes that are of the specified type will be redistributed.
internal OSPF intra-area and interarea routes or Enhanced IGRP internal routes.
external OSPF external type-1 or type-2 routes, or Enhanced IGRP external routes.
level-1 IS-IS Level 1 routes.
level-2 IS-IS Level 2 routes.

Use this form of the match command for any routes stored in the routing table with one of the tags specified:

match tag tag-value [tag-value...tag-value]
no match tag tag-value [tag-value...tag-value]
Syntax Description
tag Any routes stored in the routing table with one of the tags specified will be redistributed.
tag-value List of one or more route tags.

set route-map configuration commands

The set route-map configuration commands specify the redistribution set actions to be performed when all of a route map's match criteria are met. When all match criteria are met, all set actions are performed.

Use this form of the set command to provide a mechanism to perform conditional route aggregation as well as conditional default route advertisements:

set ip destination access-list-number
no set ip destination access-list-number
Syntax Description
destination Network to advertise instead of the one under consideration. This provides a mechanism to perform conditional route aggregation as well as conditional default route advertisements. There is no default value.
access-list-number Access list number (usually just one line long) that specifies the network to advertise.

Use this form of the set command for routes that are advertised into this specified area of the routing domain:

set level {level-1 | level-2 | level-1-2 | stub-area | backbone}
no set level {level-1 | level-2 | level-1-2 | stub-area | backbone}
Syntax Description
level Redistributed routes are advertised into this specified area of the routing domain. For IS-IS destinations, the default value is level-2. For OSPF destinations, the default value is backbone.
level-1 Inserted in IS-IS Level 1 LSPs.
level-2 Inserted in IS-IS Level 2 LSPs.
level-1-2 Inserted into both Level 1 and Level 2 IS-IS LSPs.
stub-area Inserted into OSPF Not So Stubby Areas (NSSA).
backbone Inserted into OSPF as External LSAs.

Use this form of the set command to set the metric value to give the redistributed routes:

set metric metric-value
no set metric metric-value
Syntax Description
metric Metric value to give the redistributed routes. There is no default value
metric-value Route metric. This may be an IGRP five-part metric.

Use this form of the set command to set the metric type to give redistributed routes:

set metric-type {internal | external | type-1 | type-2}
no set metric-type {internal | external | type-1 | type-2}
Syntax Description
metric-type Metric type to give redistributed routes. There is no default value.
internal IS-IS internal metric.
external IS-IS external metric.
type-1 OSPF Type 1 metric.
type-2 OSPF Type 2 metric.

Use this form of the set command to set a tag value to associate with the redistributed routes.

set tag tag-value
no set tag tag-value
Syntax Description
tag Tag value to associate with the redistributed route. If not specified, the default action is to forward the tag in the source routing protocol onto the new destination protocol.
tag-value Name for the tag.
Default

Disabled

Command Mode

route-map: global configuration
match and set: route-map configuration

Usage Guidelines

Use route maps when you wish to have detailed control over how routes are redistributed between routing processes. The destination routing protocol is the one you specify with the router global configuration command. The source routing protocol is the one you specify with the redistribute router configuration command. See the following example as an illustration of how route maps are configured.

Examples

The following example redistributes all OSPF routes into IGRP:

router igrp 109 redistribute ospf 110

The following example redistributes RIP routes with a hop count equal to 1 into OSPF. These routes will be redistributed into OSPF as external link state advertisements with a metric of 5, metric type of Type 1 and a tag equal to 1.

router ospf 109 redistribute rip route-map rip-to-ospf route-map rip-to-ospf permit match metric 1 set metric 5 set metric-type type1 set tag 1
Related Commands

redistribute
show route-map

router bgp

Use the router bgp global configuration command to configure the Border Gateway Protocol (BGP) routing process. Use the no router bgp command to remove the routing process.

router bgp autonomous-system
no router bgp
autonomous-system
Syntax Description
autonomous-system Identifies the router to other BGP routers and tags the routing information passed along.
Default

None

Command Mode

Global configuration

Usage Guidelines

This command allows you to set up a distributed routing core that automatically guarantees the loop-free exchange of routing information between autonomous systems.

Example

The following example configures a BGP process for AS 120:

router bgp 120
Related Commands

neighbor
network
(BGP)
timers bgp

router egp

Use the router egp global configuration command to configure the Exterior Gateway Protocol (EGP) routing process. To turn off the EGP routing process, use the no router egp command.

router egp remote-as
no router egp
remote-as
Syntax Description
remote-as Identifies the autonomous system (AS) number the router expects its peers to be advertising in their EGP messages.
Default

None

Command Mode

Global configuration

Usage Guidelines

You must specify the autonomous system number before starting EGP. The local AS number will be included in EGP messages sent by the router. The software does not insist that the actual remote AS number match the configured AS numbers. The output from the debug ip-egp EXEC command will advise of any discrepancies.

Example

The following example assigns a router to AS 109 and is peering with routers in AS 164:

autonomous-system 109 router egp 164
Related Commands

autonomous-system
neighbor
network
(EGP)
timers egp

router egp 0

Use the router egp 0 global configuration command to specify that a router should be considered a core gateway. Use the no router egp 0 to disable this function.

router egp 0
no router egp 0
Syntax Description

This command has no arguments or keywords.

Default

Disabled

Command Mode

Global configuration

Usage Guidelines

Core gateways are central clearinghouses of routing information. Only one core gateway process can be configured in a router.

The router egp 0 global configuration command allows a specific router to have an EGP process that will enable it to act as a peer with any reachable autonomous system and information is exchanged freely between autonomous systems.

Normally, an EGP process expects to communicate with neighbors from a single AS. Because all neighbors are in the same AS, the EGP process assumes that these neighbors all have consistent internal information. Therefore, if the EGP process is informed about a route from one of its neighbors, it will not send it out to other neighbors.

With core EGP, the assumption is that all neighbors are from different ASs, and all have inconsistent information. In this case, the EGP process distributes routes from one neighbor to all others (but not back to the originator). This allows the EGP process to be a central clearinghouse for information.

To control how an EGP process determines which neighbors will be treated as peers, use the neighbor any router configuration command with the router egp 0 global configuration command.

Example

The following example illustrates how an EGP core gateway can be configured:

access-list 1 permit 10.0.0.0 0.255.255.255 ! global access list assignment router egp 0 neighbor any 1 network 131.108.0.0
Related Commands

neighbor any
neighbor any third-party

router igrp

Use the router igrp global configuration command to configure the Interior Gateway Routing Protocol (IGRP) routing process. Use the no router igrp command to shut down the routing process on the specified AS.

router igrp autonomous-system
no router igrp autonomous-system
Syntax Description
autonomous-system Identifies the routes to the other IGRP routers and is used to tag the routing information.
Default

None

Command Mode

Global configuration

Example

The following example shows how to configure an IGRP routing process and assign AS 109:

router igrp 109
Related Command

network (IGRP)

router isis

Use the router isis global configuration command to enable the IS-IS routing protocol on your router and to specify an IS-IS process for IP. The no router isis command disables IS-IS routing.

router isis [tag]
no router isis [tag]
Syntax Description
tag (Optional.) Defines a meaningful name for a routing process. If it is not specified, a null tag is assumed and the process is referenced with a null tag. This name must be unique among all IP router processes for a given router.
Default

Disabled

Command Mode

Global configuration

Usage Guidelines

You can specify only one IS-IS process per router.

Only one IS-IS process is allowed whether you run it in integrated mode, ISO CLNS only, or IP only.

Example

The following example configures the router for IP routing and enables the IS-IS routing protocol:

ip routing router isis
Related Commands

ip router isis
net

router ospf

Use the router ospf global configuration command to enable an OSPF routing process on a router. Use the no router ospf command to terminate an individual OSPF routing process.

router ospf ospf-process-id
no router ospf
ospf-process-id
Syntax Description
ospf-process-id Internally used identification parameter for an OSPF routing process. It is locally assigned and can be any positive integer. A unique value is assigned for each OSPF routing process.
Default

Disabled

Command Mode

Global configuration

Usage Guidelines

You can specify multiple OSPF routing processes in each router.

Example

The following example shows how to configure an OSPF routing process and assign a process ID of 109:

router ospf 109
Related Command

network (OSPF)

router rip

Use the router rip global configuration command to configure the Routing Information Protocol (RIP) routing process. Turn off the RIP routing process using the no router rip command.

router rip
no router rip
Syntax Description

This command has no arguments or keywords.

Default

None

Command Mode

Global configuration

Example

The following example shows how to begin the RIP routing process:

router rip
Related Command

network (RIP)

set

See the route-map global configuration command in this chapter.

show ip bgp

Use the show ip bgp EXEC command to display a particular network in the BGP routing table.

show ip bgp [network]
Syntax Description
network (Optional.) Network number, entered to display a particular network in the BGP routing table.
Command Mode

EXEC

Sample Display

The following is sample output from the show ip bgp command:

Router# show ip bgp BGP table version is 11485, local router ID is 192.54.222.2 Status codes: * valid, > best, i - internal Origin codes: i - IGP, e - EGP, ? - incomplete Network            Next Hop       Metric    Weight       Path *> 128.128.0.0     131.192.115.3           0            ? *> 192.132.70.0    192.54.222.9            20           702 701 ? *> 152.155.0.0     131.192.4.2             0            ? *> 192.52.247.0    131.192.77.2            0            ? *> 192.74.137.0    192.54.222.9 2          0            702 701 i *> 192.139.79.0    192.54.222.9 2          0            702 701 ? *> 146.150.0.0     131.192.4.2             0            ? *> 192.75.142.0    192.54.222.9 2          0            702 701 ? *> 192.75.141.0    192.54.222.9 2          0            702 701 ? *> 142.136.0.0     192.54.222.9 2          0            702 701 ? *> 192.139.77.0    192.54.222.9 2          0            702 701 ?

Table 1-3 describes significant fields shown in the display.


Show IP BGP Field Descriptions
Field Description
BGP table version is 11485 Internal version number for the table. This is incremented any time the table changes.
local router ID An Internet address of the router.
Status codes Asterisk (*) indicates that the table entry is valid.
A > character indicates that the table entry is the best entry to use for that network.
A lowercase i indicates that the table entry was learned via an internal BGP session.
Network Internet address of the network the entry describes.
Next Hop IP address of the next system to use when forwarding a packet to the destination network. An entry of 0.0.0.0 indicates that the router has some non-BGP route to this network.
Metric If shown, is the value of the interautonomous system metric. This is frequently not used.
Weight Set through the use of AS filters.
Path Autonomous system paths to the destination network. There can be one entry in this field for each autonomous system in the path. At the end of the path is the origin code for the path.
A lowercase i indicates that the entry was originated with the IGP and advertised with a network router configuration command.
A lowercase e indicates that the route originated with EGP. A question mark (?) indicates that the origin of the path is not clear. Usually this is a path that is redistributed into BGP from an IGP

show ip bgp neighbors

Use the show ip bgp neighbors EXEC command to display detailed information on the TCP and BGP connections to individual neighbors. Use the optional form show ip bgp neighbors address routes to show the routes learned from a particular neighbor.

show ip bgp neighbors [address]
show ip bgp neighbors address [routes]
Syntax Description
address (Optional.) Address of the neighbor whose routes you have learned from.
routes (Optional.) Routes of specified neighbors.
Command Mode

EXEC

Sample Display

The following is sample output from the show ip bgp neighbors command:

Router# show ip bgp neighbors BGP neighbor is 131.108.6.68, remote AS 10, external link BGP version 3, remote router ID 131.108.6.68 BGP state = Established, table version = 22, up for 0:00:13 Last read 0:00:12, hold time is 180, keepalive interval is 60 seconds Received 24 messages, 0 notifications Sent 28 messages, 4 notifications Connections established 1; dropped 0 Connection state is ESTAB, I/O status: 1, unread input bytes: 0 Local host: 131.108.6.69, 12288 Foreign host: 131.108.6.68, 179 Enqueued packets for retransmit: 0, input: 0, saved: 0 Event Timers (current time is 835828): Timer: Retrans TimeWait AckHold SendWnd KeepAlive Starts: 20 0 18 0 0 Wakeups: 1 0 2 0 0 Next: 0 0 0 0 0 iss: 60876 snduna: 62649 sndnxt: 62649 sndwnd: 1872 irs: 95187024 rcvnxt: 95188733 rcvwnd: 1969 delrcvwnd: 271 SRTT: 364 ms, RTTO: 1691 ms, RTV: 481 ms, KRTT: 0 ms minRTT: 4 ms, maxRTT: 340 ms, ACK hold: 300 ms Flags: higher precedence Datagrams (max data segment is 1450 bytes): Rcvd: 36 (out of order: 0), with data: 18, total data bytes: 1708 Sent: 40 (retransmit: 1), with data: 36, total data bytes: 1817

Table 1-4 describes significant fields shown in the display.


Show IP BGP Neighbors Field Descriptions
Field Description
BGP neighbor Lists the IP address of the BGP neighbor and its AS number. If the neighbor is in the same AS as the router, then the link between them is internal. Otherwise, it is considered external.
BGP version Specifies that the BGP version being used to communicate with the remote router is BGP version 3; the neighbor's router ID (an IP address) is also specified.
BGP state Indicates the internal state of this BGP connection.
  table version Indicates that the neighbor has been updated with this version of the primary BGP routing table.
  up time Indicates the amount of time that the underlying TCP connection has been in existence.
Last read Time that BGP last read a message from this neighbor.
  hold time Maximum amount of time that can elapse between messages from the peer.
  keepalive interval Time period between sending keepalive packets, which help ensure that the TCP connection is up.
Received Number of received messages indicates the number of total BGP messages received from this peer, including keepalives. The number of notifications is the number of error messages received from the peer.
Sent The number of sent messages indicates the total number of BGP messages that have been sent to this peer, including keepalives. The number of notifications is the number of error messages that we have sent to this peer.
Connections established The number of connections established is a count of the number of times that we have established a TCP connection and the two peers have agreed speak BGP with each other. The number of dropped connections is the number of times that a good connection has failed or been taken down.

The remainder of the display describes the status of the underlying TCP connection.

show ip bgp paths

Use the show ip bgp paths EXEC command to display all the BGP paths in the database.

show ip bgp paths
Syntax Description

This command has no arguments or keywords.

Command Mode

EXEC

Sample Display

The following is sample output from the show ip bgp paths command:

Router# show ip bgp paths Address Hash Refcount Metric Path 0x297A9C 0 2 0 i 0x30BF84 1 0 0 702 701 ? 0x2F7BC8 2 235 0 ? 0x2FA1D8 3 0 0 702 701 i

Table 1-5 describes significant fields shown in the display.


Show IP BGP Paths Field Descriptions
Field Description
Address Internal address where the path is stored.
Hash Hash bucket where path is stored.
Refcount Number of routes using that path.
Metric The INTER_AS metric for the path.
Path The AS_PATH for that route, followed by the origin code for that route.

show ip bgp summary

Use the show ip bgp summary EXEC command to display the status of all BGP connections.

show ip bgp summary
Syntax Description

This command has no arguments or keywords.

Command Mode

EXEC

Sample Display

The following is sample output from the show ip bgp summary command:

Router# show ip bgp summary BGP table version is 3937, main routing table version 3937 Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Uptime/State 192.54.222.6 2 690 7655 268 3937 0 0 2:39:51 192.54.222.9 3 702 682 364 3937 0 0 2:39:54

Table 1-6 describes significant fields shown in the display.


Show IP BGP Summary Field Descriptions
Field Description
BGP table version Internal version number of BGP database.
main routing table version Indicates last version of BGP database that was injected into main routing table.
Neighbor IP address of a neighbor.
V Indicates BGP version number spoken to that neighbor.
MsgRcvd BGP messages received from that neighbor.
MsgSent BGP messages sent to that neighbor.
TblVer Last version of the BGP database that was sent to that neighbor.
InQ Number of messages from that neighbor waiting to be processed.
OutQ Number of messages waiting to be sent to that neighbor.
Update/State The length of time that the BGP session has been in state Established, or the current state if it is not Established.

show ip egp

Use the show ip egp EXEC command to display statistics on EGP connections and neighbors.

show ip egp
Syntax Description

This command has no arguments or keywords.

Command Mode

EXEC

Sample Display

The following is sample output from the show ip egp command:

Router# show ip egp Local autonomous system is 109 EGP Neighbor FAS/LAS State SndSeq RcvSeq Hello Poll j/k Flags 10.3.0.27 1/109 IDLE 625 61323 60 180 0 Perm, Act * 10.2.0.37 1/109 UP 12:29 250 14992 60 180 3 Perm, Act * 10.7.0.63 1/109 UP 1d19 876 10188 60 180 4 Perm, Pass

Table 1-7 describes the fields shown in the display.


Show IP EGP Field Descriptions
Field Description
EGP Neighbor Address of the EGP neighbor.
FAS Foreign autonomous system number.
LAS Local autonomous system number.
State State of the connection between peers.
SndSeq Send sequence number.
RcvSeq Receive sequence number.
Hello Interval between Hello/I-Heard-You packets.
Poll Interval between Poll/Update packets.
j/k Measure of reachability; 4 is perfect.
Flags Perm--Permanent.

Temp--Temporary (neighbor will be removed).

Act--Active, controlling the connection.

Pass--Passive, neighbor controls the connection.

show ip irdp

Use the show ip irdp EXEC command to display IRDP values.

show ip irdp
Syntax Description

This command has no arguments or keywords.

Command Mode

EXEC

Sample Display

The following is sample output from the show ip irdp command:

Router# show ip irdp Ethernet 0 has router discovery enabled Advertisements will occur between every 450 and 600 seconds. Advertisements are valid for 1800 seconds. Default preference will be 100. --More-- Serial 0 has router discovery disabled --More-- Ethernet 1 has router discovery disabled

As the display shows, show ip irdp output indicates whether or not router discovery has been configured for each router interface, and lists the values of router discovery configurables for those interfaces on which router discovery has been enabled. Explanations for the less self-evident lines of output in the display follow.

Advertisements will occur between every 450 and 600 seconds.

Indicates the configured minimum and maximum advertising interval for the interface.

Advertisements are valid for 1800 seconds.

Indicates the configured holdtime values for the interface.

Default preference will be 100.

Indicates the configured (or in this case default) preference value for the interface.

show ip ospf

Use the show ip ospf EXEC command to display general information about OSPF routing processes in a particular router.

show ip ospf [ospf-process-id]
Syntax Description
ospf-process-id (Optional.) Specific a process ID. If this argument is included, only information for the specified routing process is included.
Command Mode

EXEC

Sample Display

The following is sample output from the show ip ospf command when entered without a specific OSPF process ID:

Router# show ip ospf Routing Process "ospf 201" with ID 192.42.110.200 Supports only single TOS(TOS0) route It is an area border and autonomous system boundary router Summary Link update interval is 0:30:00 and the update due in 0:16:26 External Link update interval is 0:30:00 and the update due in 0:16:27 Redistributing External Routes from,     igrp 200 with metric mapped to 2, includes subnets in redistribution     rip with metric mapped to 2     igrp 2 with metric mapped to 100     igrp 32 with metric mapped to 1 Number of areas in this router is 3 Area 192.42.110.0     Number of interfaces in this area is 1     Area has simple password authentication     SPF algorithm executed 6 times     Area ranges are     Link State Update Interval is 0:30:00 and due in 0:16:55     Link State Age Interval is 0:20:00 and due in 0:06:55

Table 1-8 describes significant fields shown in the display.


Show IP OSPF Field Descriptions
Field Description
Routing process "ospf 201" with ID 192.42.110.200 Process ID and OSPF router ID.
Type of Service Number of Types of Service supported (Type 0 only).
Type of OSPF Router Possible types are internal, area border, or AS boundary.
Summary Link update interval Specify summary update interval in hours:minutes:seconds, and time to next update.
External Link update interval Specify external update interval in hours:minutes:seconds, and time to next update.
Redistributing External Routes from Lists of redistributed routes, by protocol.
Number of areas Number of areas in router, area addresses, and so on.
Link State Update Interval Specify router and network link state update interval in hours:minutes:seconds, and time to next update.
Link State Age Interval Specify max-aged update deletion interval and time until next database cleanup in hours:minutes:seconds.

show ip ospf border-routers

Use the show ip ospf border-routers EXEC command to display the internal OSPF routing table entries to Area Border Routers (ABRs) and Autonomous System Boundary Routers (ASBRs).

show ip ospf border-routers
Syntax Description

This command has no arguments or parameters

Command Mode

EXEC

Sample Display

The following is sample output from the show ip ospf border-routers command:

router# show ip ospf border-routers OSPF Process 109 internal Routing Table Destination Next Hop Cost Type Rte Type Area SPF No 160.89.97.53 144.144.1.53 10 ABR INTRA 0.0.0.3 3 160.89.103.51 160.89.96.51 10 ABR INTRA 0.0.0.3 3 160.89.103.52 160.89.96.51 20 ASBR INTER 0.0.0.3 3 160.89.103.52 144.144.1.53 22 ASBR INTER 0.0.0.3 3

Table 1-9 describes significant fields shown in the display.


Show IP OSPF Border-Routers Field Descriptions
Field Description
Destination Destination's router ID.
Next Hop Next hop toward the destination.
Cost Cost of using this route.
Type The router type of the destination; it is either an Area Border Router (ABR) or Autonomous System Boundary Router (ASBR) or both.
Rte Type The type of this route, it is either an intra-area or interarea route.
Area The area ID of the area that this route is learned from.
SPF No The internal number of SPF calculation that installs this route.

show ip ospf database

Use the show ip ospf database EXEC command to display lists of information related to the OSPF database for a specific router. The various forms of this command deliver information about different OSPF link state advertisements.

Syntax for the various forms of the show ip ospf database command follow.

show ip ospf [ospf-process-id area-id] database
show ip ospf [
ospf-process-id area-id] database [router] [link-state-id]
show ip ospf [
ospf-process-id area-id] database [network] [link-state-id]
show ip ospf [
ospf-process-id area-id] database [summary] [link-state-id]
show ip ospf [
ospf-process-id area-id] database [asb-summary] [link-state-id]
show ip ospf [
ospf-process-id] database [external] [link-state-id]
Command Mode

EXEC

Syntax Description
ospf-process-id

(Optional.) Internally used identification parameter. It is locally assigned and can be any positive integer number. The number used here is the number assigned administratively when enabling the OSPF routing process.
area-id

(Optional.) Area number associated with the OSPF address range defined in the network router configuration command used to define the particular area.
link-state-id

(Optional.) Identifies the portion of the Internet environment that is being described by the advertisement. The value entered depends on the advertisement's LS type. It must be entered in the form of an IP address.

When the link state advertisement is describing a network, the link-state-id can take one of two forms:

--The network's IP address (as in type 3 summary link advertisements and in AS external link advertisements).

--A derived address obtained from the link state ID. (Note that masking a network links advertisement's link state ID with the network's subnet mask yields the network's IP address.)

When the link state advertisement is describing a router, the link state ID is always the described router's OSPF router ID.

When an AS external advertisement (LS Type = 5) is describing a default route, its link state ID is set to Default Destination (0.0.0.0).

When entered with the optional keywords router, network, summary, asb-summary, and external, different displays result. Examples and brief descriptions of each form follow.

Sample Display Using Show Ip Ospf Database with No Optional Arguments or Keywords

The following is sample output from the show ip ospf database command when no optional arguments or keywords are used:

Router# show ip ospf database OSPF Router with id(190.20.239.66) (Autonomous system 300) Displaying Router Link States(Area 0.0.0.0) Link ID ADV Router Age Seq# Checksum Link count 155.187.21.6 155.187.21.6 1731 0x80002CFB 0x69BC 8 155.187.21.5 155.187.21.5 1112 0x800009D2 0xA2B8 5 155.187.1.2 155.187.1.2 1662 0x80000A98 0x4CB6 9 155.187.1.1 155.187.1.1 1115 0x800009B6 0x5F2C 1 155.187.1.5 155.187.1.5 1691 0x80002BC 0x2A1A 5 155.187.65.6 155.187.65.6 1395 0x80001947 0xEEE1 4 155.187.241.5 155.187.241.5 1161 0x8000007C 0x7C70 1 155.187.27.6 155.187.27.6 1723 0x80000548 0x8641 4 155.187.70.6 155.187.70.6 1485 0x80000B97 0xEB84 6 Displaying Net Link States(Area 0.0.0.0) Link ID ADV Router Age Seq# Checksum 155.187.1.3 192.20.239.66 1245 0x800000EC 0x82E Displaying Summary Net Link States(Area 0.0.0.0) Link ID ADV Router Age Seq# Checksum 155.187.240.0 155.187.241.5 1152 0x80000077 0x7A05 155.187.241.0 155.187.241.5 1152 0x80000070 0xAEB7 155.187.244.0 155.187.241.5 1152 0x80000071 0x95CB

Table 1-10 describes significant fields shown in the display.


Show IP OSPF Database Field Descriptions
Field Description
Link ID Router ID number.
ADV Router Advertising router's router ID.
Age Link state age.
Seq# Link state sequence number (detects old or duplicate link state advertisements).
Checksum Fletcher checksum of the complete contents of the link state advertisement.
Link count Number of interfaces detected for router.
Sample Display Using Show Ip Ospf Database Asb-Summary

The following is sample output from the show ip ospf database asb-summary command when no optional arguments are specified:

Router# show ip ospf database asb-summary OSPF Router with id(190.20.239.66) (Autonomous system 300) Displaying Summary ASB Link States(Area 0.0.0.0) LS age: 1463 Options: (No TOS-capability) LS Type: Summary Links(AS Boundary Router) Link State ID: 155.187.245.1 (AS Boundary Router address) Advertising Router: 155.187.241.5 LS Seq Number: 80000072 Checksum: 0x3548 Length: 28 Network Mask: 0.0.0.0 TOS: 0 Metric: 1

Table 1-11 describes significant fields shown in the display.


Show IP OSPF Database Asb-Summary Field Descriptions
Field Description
Router ID Router ID number.
Autonomous system OSPF autonomous system number (OSPF process ID).
LS age Link state age.
Options Type of Service options (Type 0 only).
LS Type Link state type.
Link State ID Link state ID (AS Boundary Router).
Advertising Router Advertising router's router ID.
LS Seq Number Link state sequence (detects old or duplicate link state advertisements).
Checksum LS checksum (Fletcher checksum of the complete contents of the link state advertisement).
Length Length in bytes of the link state advertisement.
Network Mask Network mask implemented.
TOS Type of Service.
Metric Link state metric.
Sample Display Using Show Ip Ospf Database External

The following is sample output from the show ip ospf database external command when no optional arguments are specified:

Router# show ip ospf database external OSPF Router with id(190.20.239.66) (Autonomous system 300) Displaying AS External Link States LS age: 280 Options: (No TOS-capability) LS Type: AS External Link Link State ID: 143.105.0.0 (External Network Number) Advertising Router: 155.187.70.6 LS Seq Number: 80000AFD Checksum: 0xC3A Length: 36 Network Mask: 255.255.0.0       Metric Type: 2 (Larger than any link state path)       TOS: 0       Metric: 1       Forward Address: 0.0.0.0       External Route Tag: 0

Table 1-12 describes significant fields shown in the display.


Show IP OSPF Database External Field Descriptions
Field Description
Router ID Router ID number.
Autonomous system OSPF autonomous system number (OSPF process ID).
LS age Link state age.
Options Type of Service options (Type 0 only).
LS Type Link state type.
Link State ID Link state ID (External Network Number).
Advertising Router Advertising router's router ID.
LS Seq Number Link state sequence number (detects old or duplicate link state advertisements).
Checksum LS checksum (Fletcher checksum of the complete contents of the link state advertisement).
Length Length in bytes of the link state advertisement.
Network Mask Network mask implemented.
  Metric Type External Type.
  TOS Type of Service.
  Metric Link state metric.
  Forward Address Forwarding address. Data traffic for the advertised destination will be forwarded to this address. If the forwarding address is set to 0.0.0.0, data traffic will be forwarded instead to the advertisement's originator.
  External Route Tag External route tag, a 32-bit field attached to each external route. This is not used by the OSPF protocol itself.
Sample Display Using Show Ip Ospf Database Network

The following is sample output from the show ip ospf database network command when no optional arguments are specified:

Router# show ip ospf database network OSPF Router with id(190.20.239.66) (Autonomous system 300) Displaying Net Link States(Area 0.0.0.0) LS age: 1367 Options: (No TOS-capability) LS Type: Network Links Link State ID: 155.187.1.3 (address of Designated Router) Advertising Router: 190.20.239.66 LS Seq Number: 800000E7 Checksum: 0x1229 Length: 52 Network Mask: 255.255.255.0 Attached Router: 190.20.239.66 Attached Router: 155.187.241.5 Attached Router: 155.187.1.1 Attached Router: 155.187.54.5 Attached Router: 155.187.1.5

Table 1-13 describes significant fields shown in the display.


Show IP OSPF Database Network Field Descriptions
Field Description
OSPF Router with ID(190.20.239.66) Router ID number.
Autonomous system 300 OSPF autonomous system number (OSPF process ID).
LS age: 1367 Link state age.
Options: (No TOS-capability) Type of Service options (Type 0 only).
LS Type: Network Links Link state type.
Link State ID Link state ID of designated router.
Advertising Router Advertising router's router ID.
LS Seq Number Link state sequence (detects old or duplicate link state advertisements).
Checksum LS checksum (Fletcher checksum of the complete contents of the link state advertisement).
Network Mask Network mask implemented.
AS Boundary Router Definition of router type.
Other fields List of routers attached to the network, by IP address.
Sample Display Using Show Ip Ospf Database Router

The following is sample output from the show ip ospf database router command when no optional arguments are specified:

Router# show ip ospf database router OSPF Router with id(190.20.239.66) (Autonomous system 300) Displaying Router Link States(Area 0.0.0.0) LS age: 1176 Options: (No TOS-capability) LS Type: Router Links Link State ID: 155.187.21.6 Advertising Router: 155.187.21.6 LS Seq Number: 80002CF6 Checksum: 0x73B7 Length: 120 AS Boundary Router 155 Number of Links: 8 Link connected to: another Router (point-to-point) (link ID) Neighboring Router ID: 155.187.21.5 (Link Data) Router Interface address: 155.187.21.6 Number of TOS metrics: 0 TOS 0 Metrics: 2

Table 1-14 describes significant fields shown in the display.


Show IP OSPF Database Router Field Descriptions
Field Description
Router ID Router ID number.
Autonomous system OSPF autonomous system number (OSPF process ID).
LS age Link state age.
Options Type of Service options (Type 0 only).
LS Type Link state type.
Link State ID Link state ID.
Advertising Router Advertising router's router ID.
LS Seq Number Link state sequence (detects old or duplicate link state advertisements).
Checksum LS checksum (Fletcher checksum of the complete contents of the link state advertisement).
Length Length in bytes of the link state advertisement.
AS Boundary Router Definition of router type.
Number of Links Number of active links.
link ID Link type.
Link Data Router interface address.
TOS Type of Service metric (Type 0 only).
Sample Display Using Show Ip Ospf Database Summary

The following is sample output from show ip ospf database summary command when no optional arguments are specified:

Router# show ip ospf database summary OSPF Router with id(190.20.239.66) (Autonomous system 300) Displaying Summary Net Link States(Area 0.0.0.0) LS age: 1401 Options: (No TOS-capability) LS Type: Summary Links(Network) Link State ID: 155.187.240.0 (summary Network Number) Advertising Router: 155.187.241.5 LS Seq Number: 80000072 Checksum: 0x84FF Length: 28 Network Mask: 255.255.255.0 TOS: 0 Metric: 1

Table 1-15 describes significant fields shown in the display.


Show IP OSPF Database Summary Field Descriptions
Field Description
Router ID Router ID number.
Autonomous system OSPF autonomous system number (OSPF process ID).
LS age Link state age.
Options Type of Service options (Type 0 only).
LS Type Link state type.
Link State ID Link state ID (summary network number).
Advertising Router Advertising router's router ID.
LS Seq Number Link state sequence (detects old or duplicate link state advertisements).
Checksum LS checksum (Fletcher checksum of the complete contents of the link state advertisement).
Length Length in bytes of the link state advertisement.
Network Mask Network mask implemented.
TOS Type of Service.
Metric Link state metric.

show ip ospf interface

Use the show ip ospf interface EXEC command to display OSPF-related interface information.

show ip ospf interface [interface-name]
Syntax Description
interface-name (Optional.) Formed either as the one-word interface description (for example, serial0, ethernet0, or fddi1), or as the two-word interface-type unit-number specification (for example, serial 0, ethernet 1, or e 2).
Command Mode

EXEC

Sample Display

The following is sample output from the show ip ospf interface command when the Ethernet 0 is specified:

Router# show ip ospf interface ethernet 0 Ethernet 0 is up, line protocol is up Internet Address 131.119.254.202, Mask 255.255.255.0, Area 0.0.0.0 AS 201, Router ID 192.77.99.1, Network Type BROADCAST, Cost: 10 Transmit Delay is 1 sec, State OTHER, Priority 1 Designated Router id 131.119.254.10, Interface address 131.119.254.10 Backup Designated router id 131.119.254.28, Interface addr 131.119.254.28 Timer intervals configured, Hello 10, Dead 60, Wait 40, Retransmit 5 Hello due in 0:00:05 Neighbor Count is 8, Adjacent neighbor count is 2    Adjacent with neighbor 131.119.254.28 (Backup Designated Router)    Adjacent with neighbor 131.119.254.10 (Designated Router)

Table 1-16 describes significant fields shown in the display.


Show IP OSPF Interface Ethernet 0 Field Descriptions
Field Description
Ethernet Status of physical link and operational status of protocol.
Internet Address Interface IP address, subnet mask, and area address.
AS AS number (OSPF process ID), router ID, network type, link state cost.
Transmit Delay Transmit delay, interface state, and router priority.
Designated Router Designated router ID and respective interface IP address.
Backup Designated router Backup designated router ID and respective interface IP address.
Timer intervals configured Configuration of timer intervals.
Hello Number of seconds until next Hello packet is sent out this interface.
Neighbor Count Count of network neighbors and list of adjacent neighbors.

show ip ospf neighbor

Use the show ip ospf neighbor EXEC command to display OSPF-neighbor information on a per-interface basis.

show ip ospf neighbor [interface-name] [neighbor-id] detail
Syntax Description
interface-name (Optional.) Formed either as the one-word interface description (for example, serial0, ethernet0, or fddi1), or as the two-word interface-type unit-number specification (for example, serial 0, ethernet 1, or e 2).
neighbor-id (Optional.) Neighbor ID.
detail Display all neighbors given in detail (list all neighbors).
Command Mode

EXEC

Sample Display

The following is sample output from the show ip ospf neighbor command showing a single line of summary information for each neighbor.

Router# show ip ospf neighbor ID Pri State Dead Time Address Interface 199.199.199.137 1 FULL/DR 0:00:31 160.89.80.37 Ethernet0 192.31.48.1 1 FULL/DROTHER 0:00:33 192.31.48.1 Fddi0 192.31.48.200 1 FULL/DROTHER 0:00:33 192.31.48.200 Fddi0 199.199.199.137 5 FULL/DR 0:00:33 192.31.48.189 Fddi0

The following is sample output showing summary information about the neighbor that matches the Neighbor ID:

Router# show ip ospf neighbor 199.199.199.137 Neighbor 199.199.199.137, interface address 160.89.80.37 In the area 0.0.0.0 via interface Ethernet0 Neighbor priority is 1, State is FULL Options 2 Dead timer due in 0:00:32 Link State retransmission due in 0:00:04 Neighbor 199.199.199.137, interface address 192.31.48.189 In the area 0.0.0.0 via interface Fddi0 Neighbor priority is 5, State is FULL Options 2 Dead timer due in 0:00:32 Link State retransmission due in 0:00:03

If you specify the interface along with the Neighbor ID, the router displays the neighbors that match the Neighbor ID on the interface, as in the following sample display:

Router# show ip ospf neighbor e 0 199.199.199.137 Neighbor 199.199.199.137, interface address 160.89.80.37 In the area 0.0.0.0 via interface Ethernet0 Neighbor priority is 1, State is FULL Options 2 Dead timer due in 0:00:37 Link State retransmission due in 0:00:04

You can also specify the interface without the Neighbor ID to show all neighbors on the specified interface, as in the following sample display:

Router# show ip ospf neighbor f 0 ID Pri State Dead Time Address Interface 192.31.48.1 1 FULL/DROTHER 0:00:33 192.31.48.1 Fddi0 192.31.48.200 1 FULL/DROTHER 0:00:32 192.31.48.200 Fddi0 199.199.199.137 5 FULL/DR 0:00:32 192.31.48.189 Fddi0

The following is sample output from the show ip ospf neighbor detail command:

Router# show ip ospf neighbor detail Neighbor 160.89.96.54, interface address 160.89.96.54 In the area 0.0.0.3 via interface Ethernet0 Neighbor priority is 1, State is FULL Options 2 Dead timer due in 0:00:38 Neighbor 160.89.103.52, interface address 160.89.103.52 In the area 0.0.0.0 via interface Serial0 Neighbor priority is 1, State is FULL Options 2 Dead timer due in 0:00:31

Table 1-17 describes significant fields shown in the previous displays.


Show IP OSPF Neighbor Field Descriptions
Field Description
Neighbor x.x.x.x Neighbor router ID.
interface address x.x.x.x IP address of the interface.
In the area Area and interface through which OSPF neighbor is known.
Neighbor priority Router priority of neighbor, neighbor state.
State OSPF state.
Options Hello packet options field contents (E-bit only; possible values are 0 and 2; 2 indicates area is not a stub; 0 indicates area is a stub.
Dead timer Expected time before router will declare neighbor dead.

show ip ospf virtual-links

Use the show ip ospf virtual-links EXEC command to display the parameters and current state of OSPF virtual links.

show ip ospf virtual-links
Syntax Description

This command has no arguments or keywords.

Command Mode

EXEC

Usage Guidelines

The information displayed by show ip ospf virtual-links is useful in debugging OSPF routing operations.

Sample Display

The following is sample output from the show ip ospf virtual-links command:

Router# show ip ospf virtual-links Virtual Link to router 160.89.101.2 is up Transit area 0.0.0.1, via interface Ethernet0, Cost of using 10 Transmit Delay is 1 sec, State POINT_TO_POINT Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5 Hello due in 0:00:08 Adjacency State FULL

Table 1-18 describes significant fields shown in the display.


Show IP OSPF Virtual-links Field Descriptions
Field Description
Virtual Link to router 160.89.101.2 is Up Specifies the OSPF neighbor, and if the link to that neighbor is Up or Down.
Transit area 0.0.0.1 The transit area through which the virtual link is formed.
via interface Ethernet0 The interface through which the virtual link is formed.
Cost of using 10 The cost of reaching the OSPF neighbor through the virtual link.
Transmit Delay is 1 sec The transmit delay on the virtual link.
State POINT_TO_POINT The state of the OSPF neighbor.
Timer intervals... The various timer intervals configured for the link.
Hello due in 0:00:08 When the next Hello is expected from the neighbor.
Adjacency State FULL The adjacency state between the neighbors.

show ip protocols

Use the show ip protocols EXEC command to display the parameters and current state of the active routing protocol process.

show ip protocols
Syntax Description

This command has no arguments or keywords.

Command Mode

EXEC

Usage Guidelines

The information displayed by show ip protocols is useful in debugging routing operations. Information in the Routing Information Sources field of the show ip protocols output can help you identify a router suspected of delivering bad routing information.

Sample Display

The following is sample output from the show ip protocols command, showing IGRP processes:

Router# show ip protocols Routing Protocol is "igrp 109"     Sending updates every 90 seconds, next due in 88 seconds    Invalid after 270 seconds, hold down for 280, flushed after 630     Outgoing update filter list for all routes is not set     Incoming update filter list for all routes is not set     Default networks flagged in outgoing updates     Default networks accepted from incoming updates     IGRP metric weight K1=1, K2=0, K3=1, K4=0, K5=0     IGRP maximum hopcount 100     Redistributing: igrp 109     Routing for Networks:       131.108.0.0       192.31.7.0 Routing Information Sources:       Gateway Distance Last Update       131.108.2.201    100        0:00:08       131.108.200.2    100        5d15       131.108.2.200    100        0:00:09      131.108.2.203    100        0:00:11

Table 1-19 describes significant fields shown in the display.


Show IP Protocols Field Descriptions
Field Description
Routing Protocol is "igrp 109" Specifies the routing protocol used.
Sending updates every 90 seconds Specifies the time between sending updates.
next due in 88 seconds Precisely when the next update is due to be sent.
Invalid after 270 seconds Specifies the value of the invalid parameter.
hold down for 280 Specifies the current value of the hold-down parameter.
flushed after 630 Specifies the time in seconds after which the individual routing information will be thrown (flushed) out.
Outgoing update ... Specifies whether the outgoing filtering list has been set.
Incoming update ... Specifies whether the incoming filtering list has been set.
Default networks Specifies how these networks will be handled in both incoming and outgoing updates.
IGRP metric Specifies the value of the K0-K5 metrics as well as the maximum hopcount.
Redistributing Lists the protocol that is being redistributed.
Routing Specifies the networks that the routing process is currently injecting routes for.
Routing Information Sources Lists all the routing sources the router is using to build its routing table. For each source, you will see displayed:

  • IP address

  • Administrative distance

  • Time the last update was received from this source.

Sample Display

The following is sample output from the show ip protocols command, showing IS-IS processes:

Router# show ip protocols Routing Protocol is "isis" Sending updates every 0 seconds Invalid after 0 seconds, hold down 0, flushed after 0 Outgoing update filter list for all interfaces is not set Incoming update filter list for all interfaces is not set Redistributing: isis Address Summarization: None Routing for Networks: Serial0 Routing Information Sources: Distance: (default is 115)

show ip route

Use the show ip route EXEC command to display the current state of the routing table.

show ip route [address [mask]] | [protocol]
Syntax Description
address (Optional.) Address about which routing information should be displayed.
mask (Optional.) Argument for a subnet mask.
protocol (Optional.) Name of a routing protocol; or the keyword connected, static, or summary. If you specify a routing protocol, use one of the following keywords: bgp, egp, eigrp, hello, igrp, isis, ospf, or rip.
Command Mode

EXEC

Sample Display

The following is sample output from the show ip route command when entered without an address:

Router# show ip route Codes: I - IGRP derived, R - RIP derived, O - OSPF derived C - connected, S - static, E - EGP derived, B - BGP derived * - candidate default route, IA - OSPF inter area route E1 - OSPF external type 1 route, E2 - OSPF external type 2 route Gateway of last resort is 131.119.254.240 to network 129.140.0.0 O E2 150.150.0.0 [160/5] via 131.119.254.6, 0:01:00, Ethernet2 E 192.67.131.0 [200/128] via 131.119.254.244, 0:02:22, Ethernet2 O E2 192.68.132.0 [160/5] via 131.119.254.6, 0:00:59, Ethernet2 O E2 130.130.0.0 [160/5] via 131.119.254.6, 0:00:59, Ethernet2 E 128.128.0.0 [200/128] via 131.119.254.244, 0:02:22, Ethernet2 E 129.129.0.0 [200/129] via 131.119.254.240, 0:02:22, Ethernet2 E 192.65.129.0 [200/128] via 131.119.254.244, 0:02:22, Ethernet2 E 131.131.0.0 [200/128] via 131.119.254.244, 0:02:22, Ethernet2 E 192.75.139.0 [200/129] via 131.119.254.240, 0:02:23, Ethernet2 E 192.16.208.0 [200/128] via 131.119.254.244, 0:02:22, Ethernet2 E 192.84.148.0 [200/129] via 131.119.254.240, 0:02:23, Ethernet2 E 192.31.223.0 [200/128] via 131.119.254.244, 0:02:22, Ethernet2 E 192.44.236.0 [200/129] via 131.119.254.240, 0:02:23, Ethernet2 E 140.141.0.0 [200/129] via 131.119.254.240, 0:02:22, Ethernet2 E 141.140.0.0 [200/129] via 131.119.254.240, 0:02:23, Ethernet2

The following is sample output that includes some IS-IS Level 2 routes learned:

Router# show ip route Codes: I - IGRP derived, R - RIP derived, O - OSPF derived C - connected, S - static, E - EGP derived, B - BGP derived i - IS-IS derived * - candidate default route, IA - OSPF inter area route E1 - OSPF external type 1 route, E2 - OSPF external type 2 route L1 - IS-IS level-1 route, L2 - IS-IS level-2 route Gateway of last resort is not set 160.89.0.0 is subnetted (mask is 255.255.255.0), 3 subnets C 160.89.64.0 255.255.255.0 is possibly down, routing via 0.0.0.0, Ethernet0 i L2 160.89.67.0 [115/20] via 160.89.64.240, 0:00:12, Ethernet0 i L2 160.89.66.0 [115/20] via 160.89.64.240, 0:00:12, Ethernet0

Table 1-20 describes significant fields shown in these two displays.


Show IP Route Field Descriptions
Field Description
O Indicates protocol that derived the route. Possible values include:

  • I--IGRP derived

  • R--RIP derived

  • O--OSPF derived

  • C--connected

  • S--static

  • E--EGP derived

  • B--BGP derived

  • i--IS-IS derived

E2

Type of route. Possible values include:

  • *--candidate default route

  • IA--OSPF interarea route

  • E1--OSPF external type 1 route

  • E2--OSPF external type 2 route

  • L1--IS-IS Level 1 route

  • L2--IS-IS Level 2 route

150.150.0.0

Indicates the address of the remote network.
[160/5] The first number in the brackets is the administrative distance of the information source; the second number is the metric for the route.
via 131.119.254.6 Specifies the address of the next router to the remote network.
0:01:00 Specifies the last time the route was updated in hours:minutes:seconds.
Ethernet 2 Specifies the interface through which the specified network can be reached.
* Round-robin pointer. It indicates the last path used when a packet was forwarded. The pointer applies to nonfast-switched packets only. The asterisk gives no indication as to which path will be used next when forwarding a nonfast-switched packet except when the paths are of equal cost.
Sample Display Using an Address

When you specify that you want information about a specific network displayed, more detailed statistics are shown. The following is sample output from the show ip route command when entered with the address 131.119.0.0.

Router# show ip route 131.119.0.0 Routing entry for 131.119.0.0 (mask 255.255.0.0)     Known via "igrp 109", distance 100, metric 10989     Tag 0     Redistributing via igrp 109     Last update from 131.108.35.13 on TokenRing0, 0:00:58 ago     Routing Descriptor Blocks:     * 131.108.35.13, from 131.108.35.13, 0:00:58 ago, via TokenRing0        Route metric is 10989, traffic share count is 1        Total delay is 45130 microseconds, minimum bandwidth is 1544 Kbit        Reliability 255/255, minimum MTU 1500 bytes        Loading 2/255, Hops 4

Table 1-21 describes significant fields shown in the display.


Show IP Route Field Descriptions
Field Description
Routing entry for 131.119.0.0 (mask 255.255.0.0) Network number and mask.
Known via "igrp 109" Indicates how the route was derived.
distance 100 Administrative distance of the information source.
Tag 0 Integer that is used to implement the route.
Redistributing via igrp 109 Indicates redistribution protocol.
Last update from 131.108.35.13 on TokenRing0 Indicates the IP address of a router that is the next hop to the remote network and the router interface on which the last update arrived.
0:00:58 ago Specifies the last time the route was updated in hours:minutes:seconds.
131.108.35.13, from 131.108.35.13, 0:00:58 ago Indicates the next hop address, the address of the gateway that sent the update, and the time that has elapsed since this update was received in hours:minutes:seconds.
via TokenRing0 Interface for this route.
Route metric is 10989 This value is the best metric for this routing descriptor block.
traffic share count is 1 Number of uses for this routing descriptor block.
Total delay is 45130 microseconds Total propagation delay in microseconds.
minimum bandwidth is 1544 Kbit Minimum bandwidth encountered when transmitting data along this route.
Reliability 255/255 Likelihood of successful packet transmission expressed as a number between 0 and 255 (255 is 100% reliability).
minimum MTU 1500 bytes Smallest MTU along the path.
Loading 2/255 Effective bandwidth of the route in kilobits per second/255 is saturation.
Hops 4 Hops to the destination or to the router where the route first enters IGRP.
Related Commands

A dagger (+) indicates that the command is documented in another chapter.

show interfaces tunnel +
show ip route summary

show ip route summary

Use the show ip route summary EXEC command to display the current state of the routing table.

show ip route summary
Syntax Description

This command has no arguments or keywords.

Command Mode

EXEC

Sample Display

The following is sample output from the show ip route summary command:

Router# show ip route summary Route Source Networks Subnets Overhead Memory (bytes) connected 0 3 126 360 static 1 2 126 360 igrp 109 747 12 31878 91080 internal 3 360 Total 751 17 32130 92160 Router#

Table 1-22 describes the fields shown in the display:


Show IP Route Summary Field Descriptions
Field Description
Route Source Routing protocol name, or connected, static, or internal.
Internal--those routes that are in the primary routing table merely as markers to hold subnet routes. These routes are not owned by any routing protocol. There should be one of these internal routes for each subnetted network in the routing table.
Networks The number of Class A, B, or C networks that are present in the routing table for each route source.
Subnets The number of subnets that are present in the routing table for each route source, including host routes.
Overhead Any additional memory involved in allocating the routes for the particular route source other than the memory specified under "Memory."
Memory The number of bytes allocated to maintain all the routes for the particular route source.
Related Command

show ip route

show isis database

The show isis database EXEC command displays the IS-IS link state database.

show isis database [level-1] [level-2] [l1] [l2] [detail] [lspid]]
Syntax Description
level-1 (Optional.) Displays the IS-IS link state database for Level 1.
level-2 (Optional.) Displays the IS-IS link state database for Level 2.
l1 (Optional.) Abbreviation for the option level-1.
l2 (Optional.) Abbreviation for the option level-2.
detail (Optional.) When specified, the contents of each LSP is displayed. Otherwise, a summary display is provided.
lspid (Optional.) Link-state protocol ID. When specified, the contents of a single LSP is displayed by its ID number.
Command Mode

EXEC

Usage Guidelines

Each of the options shown in brackets for this command can be entered in an arbitrary string within the same command entry. For example, the following are both valid command specifications and provide the same output: show isis database detail l2 and show isis database l2 detail.

Sample Display

The following is sample output from the show isis database command when it is specified with no options or as show isis database l1 l2:

Router# show isis database IS-IS Level-1 Link State Database LSPID                  LSP Seq Num     LSP Checksum   LSP Holdtime   ATT/P/OL 0000.0C00.0C35.00-00   0x0000000C      0x5696         792            0/0/0 0000.0C00.40AF.00-00*  0x00000009      0x8452         1077           1/0/0 0000.0C00.62E6.00-00   0x0000000A      0x38E7         383            0/0/0 0000.0C00.62E6.03-00   0x00000006      0x82BC         384            0/0/0 0800.2B16.24EA.00-00   0x00001D9F      0x8864         1188           1/0/0 0800.2B16.24EA.01-00   0x00001E36      0x0935         1198           1/0/0 IS-IS Level-2 Link State Database LSPID                  LSP Seq Num     LSP Checksum   LSP Holdtime   ATT/P/OL 0000.0C00.0C35.03-00   0x00000005      0x04C8         792            0/0/0 0000.0C00.3E51.00-00   0x00000007      0xAF96         758            0/0/0 0000.0C00.40AF.00-00*  0x0000000A      0x3AA9         1077           0/0/0

Table 1-23 describes significant fields shown in the display.


Show IS-IS Database Field Descriptions
Field Description
LSPID The link state PDU ID. The first six octets form the System ID. The next octet is the pseudo ID. When this value is zero, the LSP describes links from the system. When it is nonzero, the LSP is a pseudonode LSP. The designated router for an interface is the only system that originates pseudonode LSPs. The last octet is the LSP number. If there is more data than can fit in a single LSP, additional LSPs are sent with increasing LSP numbers. An asterisk (*) indicates that the LSP was originated by the local system.
LSP Seq Num Sequence number for the LSP that allows other systems to determine if they have received the latest information from the source.
LSP Checksum Checksum of the entire LSP packet.
LSP Holdtime Amount of time the LSP remains valid, in seconds.
ATT The attach bit. This indicates that the router is also a Level 2 router, and it can reach other areas.
 P The P bit. Detects if the IS is area partition repair capable.
 OL The Overload bit. Determines if the IS is congested.
Sample Display Using Show Isis Database Detail

The following is sample output from the show isis database detail command.

Router# show isis database detail IS-IS Level-1 Link State Database LSPID LSP Seq Num LSP Checksum LSP Holdtime ATT/P/OL 0000.0C00.0C35.00-00 0x0000000C 0x5696 325 0/0/0   Area Address: 47.0004.004D.0001   Area Address: 39.0001   Metric: 10 IS 0000.0C00.62E6.03   Metric: 0 ES 0000.0C00.0C35 --More-- 0000.0C00.40AF.00-00* 0x00000009 0x8452 608 1/0/0   Area Address: 47.0004.004D.0001   Metric: 10 IS 0800.2B16.24EA.01   Metric: 10 IS 0000.0C00.62E6.03   Metric: 0 ES 0000.0C00.40AF IS-IS Level-2 Link State Database LSPID LSP Seq Num LSP Checksum LSP Holdtime ATT/P/OL 0000.0C00.0C35.03-00 0x00000005 0x04C8 317 0/0/0 Metric: 0 IS 0000.0C00.0C35.00 --More-- 0000.0C00.3E51.00-00 0x00000009 0xAB98 1182 0/0/0   Area Address: 39.0004   Metric: 10 IS 0000.0C00.40AF.00   Metric: 10 IS 0000.0C00.3E51.05

As the output shows, in addition to the information displayed with show isis database, the show isis database detail command displays the contents of each LSP.

Table 1-24 describes significant fields shown in the display.


Show IS-IS Database Detail Field Descriptions
Field Description
LSPID The link state PDU ID. The first six octets form the System ID. The next octet is the pseudo ID. When this value is zero, the LSP describes links from the system. When it is nonzero, the LSP is a pseudonode LSP. The designated router for an interface is the only system that originates pseudonode LSPs. The last octet is the LSP number. If there is more data than can fit in a single LSP, additional LSPs are sent with increasing LSP numbers. An asterisk (*) indicates that the LSP was originated by the local system.
LSP Seq Num Sequence number for the LSP that allows other systems to determine if they have received the latest information from the source.
LSP Checksum Checksum of the entire LSP packet.
LSP Holdtime Amount of time the LSP remains valid, in seconds.
ATT The attach bit. This indicates that the router is also a Level 2 router, and it can reach other areas.
 P The P bit. Detects if the IS is area partition repair capable.
 OL The Overload bit. Determines if the IS is congested.
Area Address: Reachable area addresses from the router.
Metric: IS-IS metric for the route.
Sample Display Using Show Isis Database Detail Displaying IP Addresses

The following is additional sample output from the show isis database detail command.This is a Level 2 LSP. The area address 39.0001 is the address of the area in which the router resides.

Router# show isis database detail l2 IS-IS Level-2 Link State Database LSPID LSP Seq Num LSP Checksum LSP Holdtime ATT/P/OL 0000.0C00.1111.00-00* 0x00000006 0x4DB3 1194 0/0/0 Area Address: 39.0001 NLPID: 0x81 0xCC IP Address: 160.89.64.17 Metric: 10 IS 0000.0C00.1111.09 Metric: 10 IS 0000.0C00.1111.08 Metric: 10 IP 160.89.65.0 255.255.255.0 Metric: 10 IP 160.89.64.0 255.255.255.0 Metric: 0 IP-External 10.0.0.0 255.0.0.0

Table 1-25 describes significant fields shown in the display.


Show IS-IS Database Detail Field Descriptions
Field Description
LSPID The link state PDU ID. The first six octets form the System ID. The next octet is the pseudo ID. When this value is zero, the LSP describes links from the system. When it is nonzero, the LSP is a pseudonode LSP. The designated router for an interface is the only system that originates pseudonode LSPs. The last octet is the LSP number. If there is more data than can fit in a single LSP, additional LSPs are sent with increasing LSP numbers. An asterisk (*) indicates that the LSP was originated by the local system.
LSP Seq Num Sequence number for the LSP that allows other systems to determine if they have received the latest information from the source.
LSP Checksum Checksum of the entire LSP packet.
LSP Holdtime Amount of time the LSP remains valid, in seconds.
ATT The attach bit. This indicates that the router is also a Level 2 router, and it can reach other areas.
 P The P bit. Detects if the IS is area partition repair capable.
 OL The Overload bit. Determines if the IS is congested.
Area Address: Reachable area addresses from the router.
NLPID Indicates that both IP and OSI (0x0cc and 0x081 respectively) are supported in IS-IS for this router.
IP Address: The IP address for the router is advertised in the LSP.
Metric: IS-IS metric for the route.
  Various addresses The "IP" entries are the directly connected IP subnets the router is advertising (with associated metrics). The "IP-External" is a redistribute route.

show route-map

Use the show route-map EXEC command to display all route-maps configured or only the one specified.

show route-map [map-name]
Syntax Description
map-name (Optional.) Name of a specific route-map.
Command Mode

EXEC

Sample Display

The following is sample output from the show route-map command:

Router# show route-map route-map foo, permit, sequence 10 Match clauses: tag 1 2 Set clauses: metric 5 route-map foo, permit, sequence 20 Match clauses: tag 3 4 Set clauses: metric 6

Table 1-26 describes the fields shown in the display:


Show Route-map Field Descriptions
Field Description
route-map Name of the route-map.
permit Indicates that the route is redistributed as controlled by the set actions.
sequence Number that indicates the position a new route map is to have in the list of route maps already configured with the same name.
Match clauses
  tag
Match criteria--conditions under which redistribution is allowed for the current route-map.
Set clauses
  metric
Set actions--the particular redistribution actions to perform if the criteria enforced by the match commands are met.
Related Commands

redistribute
route-map

summary-address

Use the summary-address router configuration command to create aggregate IS-IS addresses. The
no summary-address command restores the default.

summary-address address mask {level-1 | level-1-2 | level-2}
no summary-address
address mask {level-1 | level-1-2 | level-2}
Syntax Description
address Summary address designated for a range of addresses.
mask IP subnet mask used for the summary route.
level-1 If level-1 is specified, only routes redistributed into Level 1 are summarized with the configured address/mask value.
level-1-2 If specified, the summary router is injected into both a Level 1 area and a Level 2 subdomain.
level-2 If level-2 is specified, routes learned by Level 1 routing will be summarized into the Level 2 backbone with the configured address/mask value.
Default

Disabled

Command Mode

Router configuration

Usage Guidelines

Multiple groups of addresses can be summarized for a given level. Routes learned from other routing protocols also can be summarized. The metric used to advertise the summary is the smallest metric of all the more specific routes. This command helps reduce the size of the routing table.

Example

In the following configuration, summary address 10.1.0.0 includes address 10.1.1, 10.1.2, 10.1.3, 10.1.4, and so forth. Only the address 10.1.0.0 is advertised in an IS-IS Level 1 Link State PDU.

summary-address 10.1.0.0 255.255.0.0 level-1

synchronization

Use the synchronization router configuration command to disable the synchronization between BGP and your IGP. The no synchronization command enables a router to advertise a network route without waiting for the IGP.

synchronization
no synchronization
Syntax Description

This command has no arguments or keywords.

Default

Enabled

Command Mode

Router configuration

Usage Guidelines

Usually, a BGP speaker does not advertise a route to an external neighbor unless that route is local or exists in the IGP. The no synchronization command allows a router to advertise a network route without waiting for the IGP. This feature allows routers within an AS to have the route before BGP makes it available to other ASs.

Use synchronization if there are routers in the AS that do not speak BGP.

Example

The following example disables route synchronization:

router bgp 120 no synchronization

timers basic (EGP, RIP, IGRP)

Use the timers basic router configuration command to adjust EGP, RIP, or IGRP network timers. The no timers basic command restores the defaults.

timers basic update invalid holddown flush [sleeptime]
no timers basic
Syntax Description
update Rate (in seconds) at which updates are sent. This is the fundamental timing parameter of the routing protocol.
invalid Interval of time (in seconds) after which a route is declared invalid; it should be three times the value of update. A route becomes invalid when there is an absence of updates that refresh the route. The route then enters holddown. The route is marked inaccessible and advertised as unreachable. However, the route is still used for forwarding packets.
holddown Interval (in seconds) during which routing information regarding better paths is suppressed. It should be at least three times the value of update. A route enters into a holddown state when an update packet is received that indicates the route is unreachable. The route is marked inaccessible and advertised as unreachable. However, the route is still used for forwarding packets. When holddown expires, routes advertised by other sources are accepted and the route is no longer inaccessible.
flush Amount of time (in seconds) that must pass before the route is removed from the routing table; the interval specified must be at least the sum of invalid and holddown. If it is less than this sum, the proper holddown interval cannot elapse, which results in a new route being accepted before the holddown interval expires.
sleeptime (Optional.) For IGRP only, interval (in milliseconds) for postponing routing updates in the event of a flash update. The sleeptime value should be less than the update time. If the sleeptime is greater than the update time, routing tables will become unsynchronized.
Default
Protocol update invalid holddown flush sleeptime
EGP N/A 1080 N/A 1200 N/A
RIP 30 180 180 240 N/A
IGRP 90 270 280 630 0
Command Mode

Router configuration

Usage Guidelines

The basic timing parameters for IGRP, EGP, and RIP are adjustable. Since these routing protocols are executing a distributed, asynchronous routing algorithm, it is important that these timers be the same for all routers in the network.


Note The current and default timer values can be seen by inspecting the output of the show ip protocols EXEC command. The relationships of the various timers should be preserved as described previously.
Examples

In the following example, updates are broadcast every 5 seconds. If a router is not heard from in 15 seconds, the route is declared unusable. Further information is suppressed for an additional 15 seconds. At the end of the suppression period, the route is flushed from the routing table.

router igrp 109 timers basic 5 15 15 30

Note that by setting a short update period, you run the risk of congesting slow-speed serial lines; however, this is not a big concern on faster-speed Ethernets and T1-rate serial lines. Also, if you have many routes in your updates, you can cause the routers to spend an excessive amount of time processing updates.

When the timers basic command is used with EGP, the update time and holddown time are ignored. For example, the commands that follow will set the invalid time for EGP to 100 seconds and the flush time to 200 seconds.

router egp 47 timers basic 0 100 0 200

timers bgp

Use the timers bgp router configuration command to adjust BGP network timers. The no timers bgp command resets the BGP timing defaults.

timers bgp keepalive holdtime
no timers bgp
Syntax Description
keepalive Frequency, in seconds, with which the router sends keepalive messages to its peer. The default is 60 seconds.
holdtime Interval, in seconds, after not receiving a keepalive message that the router declares a peer dead. The default is 180 seconds.
Default

keepalive timer = 60 seconds
holdtime timer = 180 seconds

Command Mode

Router configuration

Example

The following example changes the keepalive timer to 70 seconds and the holdtime timer to 210 seconds:

timers bgp 70 210
Related Commands

clear ip bgp
router bgp
show ip bgp

timers egp

Use the timers egp router configuration command to adjust EGP Hello and polltime network timers. The no timers egp command resets the EGP timing defaults.

timers egp hello polltime
no timers egp
Syntax Description
hello Frequency, in seconds, with which the router sends Hello messages to its peer. The default is 60 seconds.
polltime Interval, in seconds, for how frequently to exchange updates. The default is 180 seconds.
Default

Hello timer = 60 seconds
polltime timer = 180 seconds

Command Mode

Router configuration

Usage Guidelines

To change the invalid time or flush time for EGP routes, use the timers basic router configuration command.

Example

The following example changes the EGP timers to 2 minutes and 5 minutes, respectively:

timers egp 120 300
Related Commands

router egp
show ip egp
timers basic

traffic-share

Use the traffic-share router configuration command to control how traffic is distributed among routes when there are multiple routes for the same destination network that have different costs. Use the no form of the command to disable this function.

traffic-share {balanced | min}
no traffic share
{balanced | min}
Syntax Description
balanced Distributes traffic proportionately to the ratios of the metrics.
min Uses routes that have minimum costs.
Default

Traffic is distributed proportionately to the ratios of the metrics.

Command Mode

Router configuration

Usage Guidelines

This command applies to IGRP and enhanced IGRP routing protocols only. With the default setting, routes that have higher metrics represent less-preferable routes and get less traffic. Configuring traffic-share min causes the router to only divide traffic among the routes with the best metric. Other routes will remain in the routing table, but will receive no traffic.

Example

In the following example, only routes of minimum cost will be used:

router igrp 5 traffic-share min

variance

Use the variance router configuration command to control load balancing in an IGRP-based internet. The no variance command resets variance to the default value.

variance multiplier
no variance
Syntax Description
multiplier Range of metric values that will be accepted for load balancing. Acceptable values are nonzero, positive integers. Default is 1.
Default

1, or equal-cost load balancing

Command Mode

Router configuration

Usage Guidelines

Setting this value lets the router determine the feasibility of a potential route. A route is feasible if the next router in the path is closer to the destination than the current router and if the metric for the entire path is within the variance. Only paths that are feasible can be used for load balancing and included in the routing table.

If the following two conditions are met, the route is deemed feasible and can be added to the routing table:


  1. The local best metric must be greater than the metric learned from the next router.

  2. The multiplier times the local best metric for the destination must be greater than or equal to the metric through the next router.
Example

The following example sets a variance value of 4:

router igrp 109 variance 4

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