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Table Of Contents
default-information originate (OSPF)
show ip ospf retransmission-list
OSPF Commands
Use the commands in this chapter to configure and monitor the Open Shortest Path First (OSPF) routing protocol. For OSPF configuration information and examples, refer to the "Configuring OSPF" chapter of the Network Protocols Configuration Guide, Part 1.
area authentication
To enable authentication for an OSPF area, use the area authentication router configuration command. To remove an area's authentication specification or a specified area from the configuration, use the no form of this command.
area area-id authentication [message-digest]
no area area-id authentication
no area area-idSyntax Description
Default
Type 0 authentication (no authentication)
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0. The message-digest keyword first appeared in Cisco IOS Release 11.0.
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 and access servers 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 command to specify this password.
If you enable MD5 authentication with the message-digest keyword, you must configure a password with the ip ospf message-digest-key command.
To remove the area's authentication specification, use the no form of this command with the authentication keyword.
Note
To remove the specified area from the software configuration, use the command no area area-id (with no other keywords). That is, no area area-id removes all area options, such as area authentication, area default-cost, area nssa, area range, area stub, and area virtual-link.
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 0ip address 131.119.251.201 255.255.255.0ip ospf authentication-key adcdefgh!interface ethernet 1ip address 36.56.0.201 255.255.0.0ip ospf authentication-key ijklmnop!router ospf 201network 36.0.0.0 0.255.255.255 area 36.0.0.0network 131.119.0.0 0.0.255.255 area 0area 36.0.0.0 authenticationarea 0 authenticationRelated Commands
You can use the master indexes or search online to find documentation of related commands.
area default-cost
area stub
ip ospf authentication-key
ip ospf message-digest-keyarea default-cost
To specify a cost for the default summary route sent into a stub area, use the area default-cost router configuration command. To remove the assigned default route cost, use the no form of this command.
area area-id default-cost cost
no area area-id default-cost cost
no area area-idSyntax Description
Default
Cost of 1
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
The 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 and access servers 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.
Note
Example
The following example assigns a default-cost of 20 to stub network 36.0.0.0:
interface ethernet 0ip address 36.56.0.201 255.255.0.0!router ospf 201network 36.0.0.0 0.255.255.255 area 36.0.0.0area 36.0.0.0 stubarea 36.0.0.0 default-cost 20Related Commands
You can use the master indexes or search online to find documentation of related commands.
area nssa
To configure an area as a not so stubby area (NSSA), use the area nssa router configuration command. To remove the nssa distinction from the area, use the no form of this command.
area area-id nssa [no-redistribution] [default-information-originate]
no area area-id nssa
no area area-idSyntax Description
Default
No NSSA area is defined.
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Note
Example
In the following example, NSSA authentication is enabled on area 1:
router ospf1redistribute rip subnetsnetwork 172.19.92.0.0.0.0.255 area 1area 1 nssaarea range
To consolidate and summarize routes at an area boundary, use the area range router configuration command. To disable this function, use the no form of this command.
area area-id range address mask [advertise | not-advertise]
no area area-id range address mask [advertise | not-advertise]
no area area-idSyntax Description
Default
Disabled
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
The area range command is used only with area border routers (ABRs). 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 ABR. 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.
Note
Example
The following example specifies one summary route to be advertised by the ABR to other areas for all subnets on network 36.0.0.0 and for all hosts on network 192.42.110.0:
interface ethernet 0ip address 192.42.110.201 255.255.255.0!interface ethernet 1ip address 36.56.0.201 255.255.0.0!router ospf 201network 36.0.0.0 0.255.255.255 area 36.0.0.0network 192.42.110.0 0.0.0.255 area 0area 36.0.0.0 range 36.0.0.0 255.0.0.0area 0 range 192.42.110.0 255.255.255.0area stub
To define an area as a stub area, use the area stub router configuration command. To disable this function, use the no form of this command.
area area-id stub [no-summary]
no area area-id stub
no area area-idSyntax Description
area-id
Identifier for the stub area; either a decimal value or an IP address.
no-summary
(Optional) Prevents an ABR from sending summary link advertisements into the stub area.
Default
No stub area is defined.
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
You must configure the area stub command on all routers and access servers 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 ABR 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.
To further reduce the number of link state advertisements (LSA) sent into a stub area, you can configure no-summary on the ABR to prevent it from sending summary LSAs (LSA type 3) into the stub area.
Note
Example
The following example assigns a default cost of 20 to stub network 36.0.0.0:
interface ethernet 0ip address 36.56.0.201 255.255.0.0!router ospf 201network 36.0.0.0 0.255.255.255 area 36.0.0.0area 36.0.0.0 stubarea 36.0.0.0 default-cost 20Related Commands
You can use the master indexes or search online to find documentation of related commands.
area authentication
area default-costarea virtual-link
To define an OSPF virtual link, use the area virtual-link router configuration command with the optional parameters. To remove a virtual link, use the no form of this command.
area area-id virtual-link router-id [hello-interval seconds] [retransmit-interval seconds]
[transmit-delay seconds] [dead-interval seconds] [[authentication-key key] |
[message-digest-key keyid md5 key]]
no area area-id virtual-link router-id [hello-interval seconds] [retransmit-interval seconds]
[transmit-delay seconds] [dead-interval seconds] [[authentication-key key] |
[message-digest-key keyid md5 key]]
no area area-idSyntax Description
Defaults
area-id: No area ID is predefined.
router-id: No router ID is predefined.
hello-interval seconds: 10 seconds
retransmit-interval seconds: 5 seconds
transmit-delay seconds: 1 second
dead-interval seconds: 40 seconds
authentication-key key: No key is predefined.
message-digest-key keyid md5 key: No key is predefined.Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0. The following keywords and arguments first appeared in Cisco IOS Release 11.0: message-digest-key keyid md5 key.
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.
The Cisco IOS software will use the specified authentication key only when authentication is enabled for the backbone with the area area-id authentication router configuration command.
The two authentication schemes, simple text and MD5 authentication, are mutually exclusive. You can specify one or the other or neither. Any keywords and arguments you specify after authentication-key key or message-digest-key keyid md5 key are ignored. Therefore, specify any optional arguments before such a keyword-argument combination.
Note
Note
Examples
The following example establishes a virtual link with default values for all optional parameters:
router ospf 201network 36.0.0.0 0.255.255.255 area 36.0.0.0area 36.0.0.0 virtual-link 36.3.4.5The following example establishes a virtual link with MD5 authentication:
router ospf 201network 36.0.0.0 0.255.255.255 area 36.0.0.0area 36.0.0.0 virtual-link 36.3.4.5 message-digest-key 3 md5 sa5721bk47Related Commands
You can use the master indexes or search online to find documentation of related commands.
area authentication
service password-encryption
show ip ospfclear ip ospf
To clear redistribution based on the OSPF routing process ID, use the clear ip ospf command.
clear ip ospf [pid] {process | redistribution | counters [neighbor [intf] [nbr-id]]}
Syntax Description
Command Mode
Router configuration
Usage Guidelines
Use the pid option to clear only one OSPF process. If the pid option is not specified, all OSPF processes are cleared.
Example
The following example clears all OSPF processes:
clear ip ospf process!Related Commands
You can use the master indexes or search online to find documentation of related commands.
default-information originate (OSPF)
To generate a default route into an OSPF routing domain, use the default-information originate router configuration command. To disable this feature, use the no form of this command.
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]Syntax Description
Default
Disabled
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Whenever you use the redistribute or the default-information router configuration commands to redistribute routes into an OSPF routing domain, the Cisco IOS software automatically becomes an autonomous system boundary router (ASBR). However, an ASBR does not, by default, generate a default route into the OSPF routing domain. The software still must 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.
Example
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 109redistribute igrp 108 metric 100 subnetsdefault-information originate metric 100 metric-type 1Related Commands
You can use the master indexes or search online to find documentation of related commands.
redistribute
default-metric
To set default metric values for the OSPF routing protocol, use this form of the default-metric router configuration command. To return to the default state, use the no form of this command.
default-metric number
no default-metric numberSyntax Description
Default
Built-in, automatic metric translations, as appropriate for each routing protocol
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
The default-metric 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.
Example
The following example shows a router in autonomous system 109 using both the RIP and the OSPF routing protocols. The example advertises OSPF-derived routes using the RIP protocol and assigns the IGRP-derived routes a RIP metric of 10.
router ripdefault-metric 10redistribute ospf 109Related Commands
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redistribute
ip ospf authentication-key
To assign a password to be used by neighboring routers that are using OSPF's simple password authentication, use the ip ospf authentication-key interface configuration command. To remove a previously assigned OSPF password, use the no form of this command.
ip ospf authentication-key password
no ip ospf authentication-keySyntax Description
password
Any continuous string of characters that can be entered from the keyboard up to 8 bytes in length.
Default
No password is specified.
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
The password created by this command is used as a "key" that is inserted directly into the OSPF header when the Cisco IOS software 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
Example
In the following example, the authentication key is enabled with the string yourpass:
ip ospf authentication-key yourpassRelated Commands
You can use the master indexes or search online to find documentation of related commands.
ip ospf cost
To explicitly specify the cost of sending a packet on an interface, use the ip ospf cost interface configuration command. To reset the path cost to the default value, use the no form of this command.
ip ospf cost cost
no ip ospf costSyntax Description
cost
Unsigned integer value expressed as the link state metric. It can be a value in the range 1 to 65535.
Default
No default cost is predefined.
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
You can set the metric manually using this command, if you need to change the default. Using the bandwidth command changes the link cost as long as this command is not used.
The link state metric is advertised as the link cost in the 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 using the following formula:
108 ч Bandwidth
Using this 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 65ip ospf dead-interval
To set how long hello packets must not have been seen before its neighbors declare the router down, use the ip ospf dead-interval interface configuration command. To return to the default time, use the no form of this command.
ip ospf dead-interval seconds
no ip ospf dead-intervalSyntax Description
seconds
Unsigned integer that specifies the interval in seconds; the value must be the same for all nodes on the network.
Default
Four times the interval set by the ip ospf hello-interval command
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
The interval is advertised in the router's hello packets. This value must be the same for all routers and access servers on a specific network.
Example
The following example sets the OSPF dead interval to 60 seconds:
interface ethernet 1
ip ospf dead-interval 60Related Commands
You can use the master indexes or search online to find documentation of related commands.
ip ospf demand-circuit
To configure OSPF to treat the interface as an OSPF demand circuit, use the ip ospf demand-circuit interface configuration command. To remove the demand circuit designation from the interface, use the no form of this command.
ip ospf demand-circuit
no ip ospf demand-circuitSyntax Description
This command has no arguments or keywords.
Default
The circuit is not a demand circuit.
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.2.
On point-to-point interfaces, only one end of the demand circuit must be configured with this command. Periodic hellos are suppressed and periodic refreshes of LSAs do not flood the demand circuit. It allows the underlying datalink layer to be closed when the topology is stable. In point-to-multipoint topology, only the multipoint end must configured with this command.
Example
The following example sets the configures an ISDN on demand circuit:
router ospf1network 18.0.3.0.0.0.0.25 area 0interface BRIOip ospf demand-circuitip ospf hello-interval
To specify the interval between hello packets that the Cisco IOS software sends on the interface, use the ip ospf hello-interval interface configuration command. To return to the default time, use the no form of this command.
ip ospf hello-interval seconds
no ip ospf hello-intervalSyntax Description
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 command first appeared in Cisco IOS Release 10.0.
This value is advertised in the 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 and access servers on a specific network.
Example
The following example sets the interval between hello packets to 15 seconds:
interface ethernet 1ip ospf hello-interval 15Related Commands
You can use the master indexes or search online to find documentation of related commands.
ip ospf message-digest-key
To enable OSPF MD5 authentication, use the ip ospf message-digest-key interface configuration command. To remove an old MD5 key, use the no form of this command.
ip ospf message-digest-key keyid md5 key
no ip ospf message-digest-key keyidSyntax Description
Default
OSPF MD5 authentication is disabled.
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.0.
Usually, one key per interface is used to generate authentication information when sending packets and to authenticate incoming packets. The same key identifier on the neighbor router must have the same key value.
The process of changing keys is as follows. Suppose the current configuration is as follows:
interface ethernet 1ip ospf message-digest-key 100 md5 OLDYou change the configuration to the following:
interface ethernet 1ip ospf message-digest-key 101 md5 NEWThe system assumes its neighbors do not have the new key yet, so it begins a rollover process. It sends multiple copies of the same packet, each authenticated by different keys. In this example, the system sends out two copies of the same packet—the first one authenticated by key 100 and the second one authenticated by key 101.
Rollover allows neighboring routers to continue communication while the network administrator is updating them with the new key. Rollover stops once the local system finds that all its neighbors know the new key. The system detects that a neighbor has the new key when it receives packets from the neighbor authenticated by the new key.
After all neighbors have been updated with the new key, the old key should be removed. In this example, you would enter the following:
interface ethernet 1no ip ospf message-digest-key 100Then, only key 101 is used for authentication on Ethernet interface 1.
We recommend that you not keep more than one key per interface. Every time you add a new key, you should remove the old key to prevent the local system from continuing to communicate with a hostile system that knows the old key. Removing the old key also reduces overhead during rollover.
Example
The following example sets a new key 19 with the password 8ry4222:
interface ethernet 1ip ospf message-digest-key 10 md5 xvv560qleip ospf message-digest-key 19 md5 8ry4222Related Commands
You can use the master indexes or search online to find documentation of related commands.
area authentication
ip ospf name-lookup
To configure OSPF to look up Domain Name System (DNS) names for use in all OSPF show EXEC command displays, use the ip ospf name-lookup global configuration command. To disable this feature, use the no form of this command.
ip ospf name-lookup
no ip ospf name-lookupSyntax Description
This command has no arguments or keywords.
Default
Disabled
Command Mode
Global configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
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-lookupSample Display
The following is sample output from the show ip ospf database EXEC command, for example, once you have enabled the DNS name lookup feature:
Router# show ip ospf databaseOSPF 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 count160.89.41.1 router 381 0x80000003 0x93BB 4160.89.34.2 neon 380 0x80000003 0xD5C8 2Net Link States (Area 0.0.0.0)Link ID ADV Router Age Seq# Checksum160.89.32.1 router 381 0x80000001 0xC117ip ospf network
To configure the OSPF network type to a type other than the default for a given media, use the ip ospf network interface configuration command. To return to the default value, use the no form of this command.
ip ospf network {broadcast | non-broadcast | point-to-multipoint}
no ip ospf networkSyntax Description
broadcast
Sets the network type to broadcast.
non-broadcast
Sets the network type to nonbroadcast.
point-to-multipoint
Sets the network type to point-to-multipoint.
Default
Depends on the network type.
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0. The point-to-multipoint keyword first appeared in Cisco IOS Release 10.3.
Using this feature, you can configure broadcast networks as nonbroadcast multiaccess (NBMA) 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.
Configuring NBMA networks as either broadcast or nonbroadcast assumes that there are virtual circuits from every router to every router or fully meshed network. This is not true for some cases, for example, because of cost constraints or when you have only a partially meshed network. In these cases, you can configure the OSPF network type as a point-to-multipoint network. Routing between two routers that are not directly connected will go through the router that has virtual circuits to both routers. Note that you do not need to configure neighbors when using this feature.
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 160.89.77.17 255.255.255.0ip ospf network broadcastencapsulation frame-relayRelated Commands
You can use the master indexes or search online to find documentation of related commands.
frame-relay map
neighbor (OSPF)
x25 mapip ospf priority
To set the router priority, which helps determine the designated router for this network, use the ip ospf priority interface configuration command. To return to the default value, use the no form of this command.
ip ospf priority number
no ip ospf prioritySyntax Description
Default
Priority of 1
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
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 4Related Commands
You can use the master indexes or search online to find documentation of related commands.
ip ospf network
neighbor (OSPF)ip ospf retransmit-interval
To specify the time between link state advertisement retransmissions for adjacencies belonging to the interface, use the ip ospf retransmit-interval interface configuration command. To return to the default value, use the no form of this command.
ip ospf retransmit-interval seconds
no ip ospf retransmit-intervalSyntax Description
Default
5 seconds
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
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 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 8ip ospf transmit-delay
To set the estimated time it takes to transmit a link state update packet on the interface, use the ip ospf transmit-delay interface configuration command. To return to the default value, use the no form of this command.
ip ospf transmit-delay seconds
no ip ospf transmit-delaySyntax Description
seconds
Time in seconds that it takes to transmit a link state update.The range is 1 to 65535 seconds. The default is 1 second.
Default
1 second
Command Mode
Interface configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Link state advertisements in the update packet must have their ages incremented by the amount specified in the 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 3neighbor (OSPF)
To configure OSPF routers interconnecting to nonbroadcast networks, use this form of the neighbor router configuration command. To remove a configuration, use the no form of this command.
neighbor ip-address [priority number] [poll-interval seconds]
no neighbor ip-address [priority number] [poll-interval seconds]Syntax Description
Default
No configuration is specified.
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
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 commands in "X.25 Commands" and "Frame Relay Commands" chapters, respectively, in the Wide-Area Networking Command Reference for more detail.
One neighbor entry must be included in the Cisco IOS software 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 Dead Interval 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 backup 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.
Note
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 180Related Commands
You can use the master indexes or search online to find documentation of related commands.
network area
To define the interfaces on which OSPF runs and to define the area ID for those interfaces, use the network area router configuration command. To disable OSPF routing for interfaces defined with the address wildcard-mask pair, use the no form of this command.
network address wildcard-mask area area-id
no network address wildcard-mask area area-idSyntax Description
Default
Disabled
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
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.
For OSPF to operate on the interface, that interface's primary address must be covered by the network area command. If the network area command covers only the secondary address, it will not enable OSPF over that interface.
The Cisco IOS software sequentially evaluates the address/wildcard-mask pair for each interface as follows:
1
2
3
4
There is no limit to the number of network area commands used on the router.
Note
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.
interface ethernet 0ip address 131.108.20.1 255.255.255.0router ospf 109network 131.108.20.0 0.0.0.255 area 10.9.50.0network 131.108.0.0 0.0.255.255 area 2network 131.109.10.0 0.0.0.255 area 3network 0.0.0.0 255.255.255.255 area 0Related Commands
You can use the master indexes or search online to find documentation of related commands.
ospf auto-cost
To control how OSPF calculates default metrics for the interface, use the ospf auto-cost router configuration command. To assign cost based only on the interface type, use the no form of this command.
ospf auto-cost reference-bandwidth ref-bw
no ospf auto-cost reference-bandwidthSyntax Description
Default
100 Mbits
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.2.
In Cisco IOS Release 10.3 and later, by default OSPF will calculate the OSPF metric for an interface according to the bandwidth of the interface. For example, a 64K link will get a metric of 1562, while a T1 link will have a metric of 64.
The OSPF metric is calculated as ref-bw divided by bandwidth, with ref-bw equal to 108 by default, and bandwidth determined by the bandwidth command. The calculation gives FDDI a metric of 1.
If you have multiple links with high bandwidth (such as FDDI or ATM), you might want to use a larger number to differentiate the cost on those links.
The value set by the ip ospf cost command overrides the cost resulting from the ospf auto-cost command.
Example
The following example changes the cost of the FDDI link to 10, while the gigabit Ethernet link remains at a cost of 1. Thus, the link costs are differentiated.
router ospf 1ospf auto-cost reference-bandwidth 1000Related Commands
You can use the master indexes or search online to find documentation of related commands.
ospf log-adj-changes
To configure the router to send a syslog message when the state of an OSPF neighbor changes, use the ospf log-adj-changes router configuration command. To turn off this feature, use the no form of this command.
ospf log-adj-changes
no ospf log-adj-changesSyntax Description
This command has no arguments or keywords.
Default
No such syslog message is sent.
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 11.2.
Configure this command if you want to know about OSPF neighbor changes without turning on the debugging command debug ip ospf adjacency. The ospf log-adj-changes command provides a higher level view of changes to the state of the peer relationship with less output.
Example
The following example configures the router to send a syslog message for any neighbor state changes:
ospf log-adj-changesrouter-id
To use a fixed router-id, use the router-id command. To force OSPF to use the previous OSPF router-id behavior, use the no form of this command.
router-id ip-address
no router-idSyntax Description
Default
No OSPF routing process is defined.
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
You can configure an arbitrary value in the ip-address format for each router. However, each router ID must be unique.
If this command is used on an OSPF router process which is already active (has neighbors), the new router-id is used at the next reload or at a manual OSPF process restart. To manually restart the OSPF process, use the clear ip ospf command.
Example
The following example specifies a fixed router-id:
router-id 1.1.1.1Related Commands
You can use the master indexes or search online to find documentation of related commands.
router ospf
To configure an OSPF routing process, use the router ospf global configuration command. To terminate an OSPF routing process, use the no form of this command.
router ospf process-id
router-id [ip-address]
no router ospf process-idSyntax Description
Default
No OSPF routing process is defined.
Command Mode
Global configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
You can specify multiple OSPF routing processes in each router.
You can configure an arbitrary value in the ip-address format for each router. However, each router ID must be unique.
Example
The following example shows how to configure an OSPF routing process and assign a process number of 109:
router ospf 109Related Commands
You can use the master indexes or search online to find documentation of related commands.
show ip ospf
To display general information about OSPF routing processes, use the show ip ospf EXEC command.
show ip ospf [process-id]
Syntax Description
process-id
(Optional) Process ID. If this argument is included, only information for the specified routing process is included.
Command Mode
EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Sample Display
The following is sample output from the show ip ospf command when entered without a specific OSPF process ID:
Router# show ip ospfRouting Process "ospf 201" with ID 192.42.110.200Supports only single TOS(TOS0) routeIt is an area border and autonomous system boundary routerSummary Link update interval is 0:30:00 and the update due in 0:16:26External Link update interval is 0:30:00 and the update due in 0:16:27Redistributing External Routes from,igrp 200 with metric mapped to 2, includes subnets in redistributionrip with metric mapped to 2igrp 2 with metric mapped to 100igrp 32 with metric mapped to 1Number of areas in this router is 3Area 192.42.110.0Number of interfaces in this area is 1Area has simple password authenticationSPF algorithm executed 6 timesArea ranges areLink State Update Interval is 0:30:00 and due in 0:16:55Link State Age Interval is 0:20:00 and due in 0:06:55describes significant fields shown in the display.
show ip ospf border-routers
To display the internal OSPF routing table entries to an area border router (ABR) and autonomous system boundary router (ASBR), use the show ip ospf border-routers privileged EXEC command.
show ip ospf border-routers
Syntax Description
This command has no arguments or keywords.
Command Mode
Privileged EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Sample Display
The following is sample output from the show ip ospf border-routers command:
Router# show ip ospf border-routersOSPF Process 109 internal Routing TableDestination Next Hop Cost Type Rte Type Area SPF No160.89.97.53 144.144.1.53 10 ABR INTRA 0.0.0.3 3160.89.103.51 160.89.96.51 10 ABR INTRA 0.0.0.3 3160.89.103.52 160.89.96.51 20 ASBR INTER 0.0.0.3 3160.89.103.52 144.144.1.53 22 ASBR INTER 0.0.0.3 3describes the fields shown in the display.
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.
show ip ospf [process-id area-id] database
show ip ospf [process-id area-id] database [router] [link-state-id]
show ip ospf [process-id area-id] database [network] [link-state-id]
show ip ospf [process-id area-id] database [summary] [link-state-id]
show ip ospf [process-id area-id] database [asb-summary] [link-state-id]
show ip ospf [process-id area-id] database [nssa-external] [link-state-id]
show ip ospf [process-id] database [external] [link-state-id]
show ip ospf [process-id area-id] database [database-summary]Syntax Description
When entered with the optional keyword asb-summary, external, network, router, summary, or database-summary, different displays result. Examples and brief descriptions of each form follow.
Command Mode
EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0. The following form of the command first appeared in Cisco IOS Release 11.0:
show ip ospf [process-id area-id] database [database-summary].
Sample Display of Show IP OSPF Database with No Arguments or Keywords
The following is sample output from the show ip ospf database command when no arguments or keywords are used:
Router# show ip ospf databaseOSPF Router with id(190.20.239.66) (Process ID 300)Displaying Router Link States(Area 0.0.0.0)Link ID ADV Router Age Seq# Checksum Link count155.187.21.6 155.187.21.6 1731 0x80002CFB 0x69BC 8155.187.21.5 155.187.21.5 1112 0x800009D2 0xA2B8 5155.187.1.2 155.187.1.2 1662 0x80000A98 0x4CB6 9155.187.1.1 155.187.1.1 1115 0x800009B6 0x5F2C 1155.187.1.5 155.187.1.5 1691 0x80002BC 0x2A1A 5155.187.65.6 155.187.65.6 1395 0x80001947 0xEEE1 4155.187.241.5 155.187.241.5 1161 0x8000007C 0x7C70 1155.187.27.6 155.187.27.6 1723 0x80000548 0x8641 4155.187.70.6 155.187.70.6 1485 0x80000B97 0xEB84 6Displaying Net Link States(Area 0.0.0.0)Link ID ADV Router Age Seq# Checksum155.187.1.3 192.20.239.66 1245 0x800000EC 0x82EDisplaying Summary Net Link States(Area 0.0.0.0)Link ID ADV Router Age Seq# Checksum155.187.240.0 155.187.241.5 1152 0x80000077 0x7A05155.187.241.0 155.187.241.5 1152 0x80000070 0xAEB7155.187.244.0 155.187.241.5 1152 0x80000071 0x95CBdescribes significant fields shown in the display.
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-summaryOSPF Router with id(190.20.239.66) (Process ID 300)Displaying Summary ASB Link States(Area 0.0.0.0)LS age: 1463Options: (No TOS-capability)LS Type: Summary Links(AS Boundary Router)Link State ID: 155.187.245.1 (AS Boundary Router address)Advertising Router: 155.187.241.5LS Seq Number: 80000072Checksum: 0x3548Length: 28Network Mask: 0.0.0.0 TOS: 0 Metric: 1describes significant fields shown in the display.
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 externalOSPF Router with id(190.20.239.66) (Autonomous system 300)Displaying AS External Link StatesLS age: 280Options: (No TOS-capability)LS Type: AS External LinkLink State ID: 143.105.0.0 (External Network Number)Advertising Router: 155.187.70.6LS Seq Number: 80000AFDChecksum: 0xC3ALength: 36Network Mask: 255.255.0.0Metric Type: 2 (Larger than any link state path)TOS: 0Metric: 1Forward Address: 0.0.0.0External Route Tag: 0describes significant fields shown in the display.
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 networkOSPF Router with id(190.20.239.66) (Process ID 300)Displaying Net Link States(Area 0.0.0.0)LS age: 1367Options: (No TOS-capability)LS Type: Network LinksLink State ID: 155.187.1.3 (address of Designated Router)Advertising Router: 190.20.239.66LS Seq Number: 800000E7Checksum: 0x1229Length: 52Network Mask: 255.255.255.0Attached Router: 190.20.239.66Attached Router: 155.187.241.5Attached Router: 155.187.1.1Attached Router: 155.187.54.5Attached Router: 155.187.1.5describes significant fields shown in the display.
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 routerOSPF Router with id(190.20.239.66) (Process ID 300)Displaying Router Link States(Area 0.0.0.0)LS age: 1176Options: (No TOS-capability)LS Type: Router LinksLink State ID: 155.187.21.6Advertising Router: 155.187.21.6LS Seq Number: 80002CF6Checksum: 0x73B7Length: 120AS Boundary Router155 Number of Links: 8Link connected to: another Router (point-to-point)(link ID) Neighboring Router ID: 155.187.21.5(Link Data) Router Interface address: 155.187.21.6Number of TOS metrics: 0TOS 0 Metrics: 2describes significant fields shown in the display.
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 summaryOSPF Router with id(190.20.239.66) (Process ID 300)Displaying Summary Net Link States(Area 0.0.0.0)LS age: 1401Options: (No TOS-capability)LS Type: Summary Links(Network)Link State ID: 155.187.240.0 (summary Network Number)Advertising Router: 155.187.241.5LS Seq Number: 80000072Checksum: 0x84FFLength: 28Network Mask: 255.255.255.0 TOS: 0 Metric: 1describes significant fields shown in the display.
Sample Display Using Show IP OSPF Database Database-Summary
The following is sample output from show ip ospf database database-summary command when no optional arguments are specified:
Router# show ip ospf database database-summaryOSPF Router with ID (172.19.65.21) (Process ID 1)Area ID Router Network Sum-Net Sum-ASBR Subtotal Delete Maxage202 1 0 0 0 1 0 0AS External 0 0 0Total 1 0 0 0 1describes significant fields shown in the display.
show ip ospf interface
To display OSPF-related interface information, use the show ip ospf interface EXEC command.
show ip ospf interface [type number]
Syntax Description
Command Mode
EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Sample Display
The following is sample output of the show ip ospf interface command when Ethernet 0 is specified:
Router# show ip ospf interface ethernet 0Ethernet 0 is up, line protocol is upInternet Address 131.119.254.202, Mask 255.255.255.0, Area 0.0.0.0AS 201, Router ID 192.77.99.1, Network Type BROADCAST, Cost: 10Transmit Delay is 1 sec, State OTHER, Priority 1Designated Router id 131.119.254.10, Interface address 131.119.254.10Backup Designated router id 131.119.254.28, Interface addr 131.119.254.28Timer intervals configured, Hello 10, Dead 60, Wait 40, Retransmit 5Hello due in 0:00:05Neighbor Count is 8, Adjacent neighbor count is 2Adjacent with neighbor 131.119.254.28 (Backup Designated Router)Adjacent with neighbor 131.119.254.10 (Designated Router)describes significant fields shown in the display.
show ip ospf neighbor
To display OSPF-neighbor information on a per-interface basis, use the show ip ospf neighbor EXEC command.
show ip ospf neighbor [type number] [neighbor-id] [detail]
Syntax Description
type
(Optional) Interface type.
number
(Optional) Interface number.
neighbor-id
(Optional) Neighbor ID.
detail
(Optional) Displays all neighbors given in detail (list all neighbors).
Command Mode
EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Sample Displays
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 neighborID Pri State Dead Time Address Interface199.199.199.137 1 FULL/DR 0:00:31 160.89.80.37 Ethernet0192.31.48.1 1 FULL/DROTHER 0:00:33 192.31.48.1 Fddi0192.31.48.200 1 FULL/DROTHER 0:00:33 192.31.48.200 Fddi0199.199.199.137 5 FULL/DR 0:00:33 192.31.48.189 Fddi0The following is sample output showing summary information about the neighbor that matches the neighbor ID:
Router# show ip ospf neighbor 199.199.199.137Neighbor 199.199.199.137, interface address 160.89.80.37In the area 0.0.0.0 via interface Ethernet0Neighbor priority is 1, State is FULLOptions 2Dead timer due in 0:00:32Link State retransmission due in 0:00:04Neighbor 199.199.199.137, interface address 192.31.48.189In the area 0.0.0.0 via interface Fddi0Neighbor priority is 5, State is FULLOptions 2Dead timer due in 0:00:32Link State retransmission due in 0:00:03If you specify the interface along with the Neighbor ID, the Cisco IOS software displays the neighbors that match the neighbor ID on the interface, as in the following sample display:
Router# show ip ospf neighbor ethernet 0 199.199.199.137Neighbor 199.199.199.137, interface address 160.89.80.37In the area 0.0.0.0 via interface Ethernet0Neighbor priority is 1, State is FULLOptions 2Dead timer due in 0:00:37Link State retransmission due in 0:00:04You 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 fddi 0ID Pri State Dead Time Address Interface192.31.48.1 1 FULL/DROTHER 0:00:33 192.31.48.1 Fddi0192.31.48.200 1 FULL/DROTHER 0:00:32 192.31.48.200 Fddi0199.199.199.137 5 FULL/DR 0:00:32 192.31.48.189 Fddi0The following is sample output from the show ip ospf neighbor detail command:
Router# show ip ospf neighbor detailNeighbor 160.89.96.54, interface address 160.89.96.54In the area 0.0.0.3 via interface Ethernet0Neighbor priority is 1, State is FULLOptions 2Dead timer due in 0:00:38Neighbor 160.89.103.52, interface address 160.89.103.52In the area 0.0.0.0 via interface Serial0Neighbor priority is 1, State is FULLOptions 2Dead timer due in 0:00:31describes the fields shown in the displays.
show ip ospf request-list
To display a list of all link state advertisements (LSAs) requested by a router, use the show ip ospf request-list EXEC command.
show ip ospf request-list [nbr] [intf] [intf-nbr]
Syntax Description
Command Mode
EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 10.2.
Sample Displays
The following is sample output from the show ip ospf request-list command:
router# show ip ospf request-list se0OSPF Router with ID (200.1.1.11) (Process ID 1)Neighbor 200.1.1.12, interface Serial0 address 144.1.1.12Type LS ID ADV RTR Seq NO Age Checksum1 200.1.1.12 200.1.1.12 0x8000020D 8 0x6572show ip ospf retransmission-list
To display a list of all link state advertisements (LSAs) waiting to be retransmitted, use the show ip ospf retransmission-list EXEC command.
show ip ospf retransmission-list [nbr] [intf] [intf-nbr]
Syntax Description
Command Mode
EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 10.2.
Sample Displays
The following is sample output from the show ip ospf retransmission-list command:
Router# show ip ospf retransmission-list se0OSPF Router with ID (200.1.1.12) (Process ID 1)Neighbor 200.1.1.11, interface Serial0 address 144.1.1.11Link state retransmission due in 3764 msec, Queue length 2Type LS ID ADV RTR Seq NO Age Checksum1 200.1.1.12 200.1.1.12 0x80000210 0 0xB196show ip ospf summary-address
To display a list of all summary address redistribution information configured under an OSPF process, use the show ip ospf summary-address EXEC command.
show ip ospf [process-id] summary-address
Syntax Description
Command Mode
EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
The process-id can be entered as a decimal number or as an IP address format.
Sample Displays
The following is sample output from the show ip ospf summary-address command:
Router# show ip ospf summary-addressOSPF Process 2, Summary-address1.2.0.0/255.255.0.0 Metric -1, Type 0, Tag 01.2.0.0/255.255.0.0 Metric -1, Type 0, Tag 10show ip ospf virtual-links
To display parameters about and the current state of OSPF virtual links, use the show ip ospf virtual-links EXEC command.
show ip ospf virtual-links
Syntax Description
This command has no arguments or keywords.
Command Mode
EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
The information displayed by the show ip ospf virtual-links command 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-linksVirtual Link to router 160.89.101.2 is upTransit area 0.0.0.1, via interface Ethernet0, Cost of using 10Transmit Delay is 1 sec, State POINT_TO_POINTTimer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5Hello due in 0:00:08Adjacency State FULLdescribes significant fields shown in the display.
summary-address
Use the summary-address router configuration command to create aggregate addresses for OSPF. The no summary-address command restores the default.
summary-address address mask {level-1 | level-1-2 | level-2} prefix mask [not-advertise]
[tag tag]
no summary-address address mask {level-1 | level-1-2 | level-2}Syntax Description
Default
Disabled
Command Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0.
Routes learned from other routing protocols 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.
Using this command for OSPF causes an OSPF autonomous system boundary router (ASBR) to advertise one external route as an aggregate for all redistributed routes that are covered by the address. For OSPF, this command summarizes only routes from other routing protocols that are being redistributed into OSPF. Use the area range command for route summarization between OSPF areas.
Example
In the following example, summary address 10.1.0.0 includes address 10.1.1.0, 10.1.2.0, 10.1.3.0, and so forth. Only the address 10.1.0.0 is advertised in an external link state advertisement.
summary-address 10.1.0.0 255.255.0.0Related Commands
You can use the master indexes or search online to find documentation of related commands.
area range
ip ospf authentication-key
ip ospf message-digest-keytimers spf
To configure the delay time between when OSPF receives a topology change and when it starts a shortest path first (SPF) calculation, and the hold time between two consecutive SPF calculations, use the timers spf router configuration command. To return to the default timer values, use the no form of this command.
timers spf spf-delay spf-holdtime
no timers spf spf-delay spf-holdtimeSyntax Description
Defaults
spf-delay: 5 seconds
spf-holdtime: 10 secondsCommand Mode
Router configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.3.
Setting the delay and hold time low causes routing to switch to the alternate path more quickly in the event of a failure. However, it consumes more CPU processing time.
Example
The following example changes the delay to 10 seconds and the hold time to 20 seconds:
timers spf 10 20
Posted: Tue Oct 12 16:54:07 PDT 2004
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