|
|
Use the commands in this chapter to configure and monitor IP Enhanced IGRP. For configuration information and examples, refer to the "Configuring IP Enhanced IGRP" chapter of the Network Protocols Configuration Guide, Part 1.
To restore the default behavior of automatic summarization of subnet routes into network-level routes, use the auto-summary router configuration command. To disable this feature and transmit subprefix routing information across classful network boundaries, use the no form of this command.
auto-summaryThis command has no arguments or keywords.
Enabled (the software summarizes subprefixes to the classful network boundary when crossing classful network boundaries).
Router configuration
This command first appeared in Cisco IOS Release 10.0.
Route summarization reduces the amount of routing information in the routing tables.
By default, BGP does not accept subnets redistributed from IGP. To advertise and carry subnet routes in BGP, use an explicit network command or the no auto-summary command. If you disable auto-summarization and have not entered a network command, you will not advertise network routes for networks with subnet routes unless they contain a summary route.
IP Enhanced IGRP summary routes are given an administrative distance value of 5. You cannot configure this value.
The following example disables automatic summarization for process eigrp 109:
router eigrp 109
no auto-summary
You can use the master indexes or search online to find documentation of related commands.
To delete entries from the neighbor table, use the clear ip eigrp neighbors EXEC command.
clear ip eigrp neighbors [ip-address | type number]
ip-address | (Optional) Address of the neighbor. |
type number | (Optional) Interface type and number. Specifying these arguments removes from the neighbor table all entries learned via this interface. |
EXEC
This command first appeared in Cisco IOS Release 10.0.
The following example removes the neighbor whose address is 160.20.8.3:
clear ip eigrp neighbors 160.20.8.3
You can use the master indexes or search online to find documentation of related commands.
To control the candidate default routing information between IGRP or Enhanced IGRP processes, use the default-information router configuration command. To suppress IGRP or Enhanced IGRP candidate information in incoming updates, use the no default-information in command. To suppress IGRP or Enhanced IGRP candidate information in outbound updates, use the no default-information out command.
default-information {in | out} {access-list-number | name}
in | Allows IGRP or Enhanced IGRP exterior or default routes to be received by an IGRP process. |
out | Allows IGRP or Enhanced IGRP exterior routes to be advertised in updates. |
access-list-number | name | Number or name of an access list. It can be a number in the range 1 to 99 or an access list name. |
Normally, exterior routes are always accepted and default information is passed between IGRP or Enhanced IGRP processes when doing redistribution.
Router configuration
This command first appeared in Cisco IOS Release 10.0. The access-list-number and name arguments first appeared in Cisco IOS Release 11.2.
The default network of 0.0.0.0 used by RIP cannot be redistributed by IGRP or Enhanced IGRP.
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 in
The following example allows IP Enhanced IGRP exterior or default routes to be received by the IP Enhanced IGRP process in autonomous system 23:
router eigrp 23
default-information in
To set metrics for IGRP or Enhanced IGRP, use this form of the default-metric router configuration command. To remove the metric value and restore the default state, use the no form of this command.
default-metric bandwidth delay reliability loading mtu
bandwidth | Minimum bandwidth of the route in kilobits per second. It can be 0 or any positive integer. |
delay | Route delay in tens of microseconds. It can be 0 or any positive number that is a multiple of 39.1 nanoseconds. |
reliability | Likelihood of successful packet transmission expressed as a number between 0 and 255. The value 255 means 100 percent reliability; 0 means no reliability. |
loading | Effective bandwidth of the route expressed as a number from 0 to 255 (255 is 100 percent loading). |
mtu | Minimum maximum transmission unit (MTU) size of the route in bytes. It can be 0 or any positive integer. |
Only connected routes and interface static routes can be redistributed without a default metric.
Router configuration
This command first appeared in Cisco IOS Release 10.0.
A default metric is required to redistribute a protocol into IGRP or Enhanced IGRP, unless you use the redistribute command. Automatic metric translations occur between IGRP and Enhanced IGRP. You do not need default metrics to redistributed IGRP or Enhanced IGRP into itself.
Metric defaults have been carefully set to work for a wide variety of networks. Take great care in changing these values.
Keeping the same metrics is supported only when redistributing from IGRP, Enhanced IGRP, or static routes.
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
You can use the master indexes or search online to find documentation of related commands.
redistribute
To allow the use of two administrative distances—internal and external—that could be a better route to a node, use the distance eigrp router configuration command. To reset these values to their defaults, use the no form of this command.
distance eigrp internal-distance external-distance
internal-distance | Administrative distance for Enhanced IGRP internal routes. Internal routes are those that are learned from another entity within the same autonomous system. It can be a value from 1 to 255. |
external-distance | Administrative distance for Enhanced IGRP external routes. External routes are those for which the best path is learned from a neighbor external to the autonomous system. It can be a value from 1 to 255. |
internal-distance: 90
external-distance: 170
Router configuration
This command first appeared in Cisco IOS Release 10.0.
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 the distance eigrp command if another protocol is known to be able to provide a better route to a node than was actually learned via external Enhanced IGRP or if some internal routes should really be preferred by Enhanced IGRP.
Table 38 lists the default administrative distances.
| Route Source | Default Distance |
|---|---|
Connected interface | 0 |
Static route | 1 |
Enhanced IGRP summary route | 5 |
External BGP | 20 |
Internal Enhanced IGRP | 90 |
IGRP | 100 |
110 | |
IS-IS | 115 |
120 | |
EGP | 140 |
EIGRP external route | 170 |
Internal BGP | 200 |
Unknown | 255 |
To display the default administrative distance for a specified routing process, use the show ip protocols EXEC command.
In the following example, the router eigrp global configuration command sets up Enhanced IGRP routing in autonomous system number 109. The network router configuration commands specify Enhanced 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 Cisco IOS software to ignore all routing updates from routers for which an explicit distance has not been set. The second distance router configuration command sets the administrative distance for all routers on the Class C network 192.31.7.0 to 90. The third distance router configuration command sets the administrative distance for the router with the address 128.88.1.3 to 120.
router eigrp 109
network 192.31.7.0
network 128.88.0.0
distance 255
!
! use caution when executing the next two commands!
!
distance 90 192.31.7.0 0.0.0.255
distance 120 128.88.1.3 0.0.0.0
You can use the master indexes or search online to find documentation of related commands.
show ip protocols
To enable the logging of changes in Enhanced IGRP neighbor adjacencies, use the eigrp log-neighbor-change router configuration command. To disable the logging of changes in Enhanced IGRP neighbor adjacencies, use the no form of this command.
eigrp log-neighbor-changesThis command has not arguments or keywords.
No adjacency changes are logged.
Router configuration
This command first appeared in Cisco IOS Release 11.2.
Enables the logging of neighbor adjacency changes to monitor the stability of the routing system and to help detect problems.
The following configuration will log neighbor changes for Enhanced IGRP process 209:
router eigrp 209
eigrp log-neighbor-changes
To enable authentication of IP Enhanced IGRP packets, use the ip authentication key-chain eigrp interface configuration command. To disable such authentication, use the no form of this command.
ip authentication key-chain eigrp autonomous-system key-chain
autonomous-system | Autonomous system to which the authentication applies. |
key-chain | Name of the authentication key chain. |
No authentication is provided for Enhanced IGRP packets.
Interface configuration
This command first appeared in Cisco IOS Release 11.2 F.
The following example applies authentication to autonomous system 2 and identifies a key chain named sports:
ip authentication key-chain eigrp 2 sports
You can use the master indexes or search online to find documentation of related commands.
accept-lifetime
ip authentication mode eigrp
key
key chain
key-string
send-lifetime
To specify the type of authentication used in IP Enhanced IGRP packets, use the ip authentication mode eigrp interface configuration command. To disable that type of authentication, use the no form of this command.
ip authentication mode eigrp autonomous-system md5
autonomous-system | Autonomous system number. |
md5 | Keyed MD5 authentication. |
No authentication is provided for IP Enhanced IGRP packets.
Interface configuration
This command first appeared in Cisco IOS Release 11.2 F.
Configure authentication to prevent unapproved sources from introducing unauthorized or false routing messages. When authentication is configured, an MD5 keyed digest is added to each Enhanced IGRP packet in the specified autonomous system.
The following example configures the interface to use MD5 authentication in Enhanced IGRP packets in autonomous system 10:
ip authentication mode eigrp 10 md5
You can use the master indexes or search online to find documentation of related commands.
accept-lifetime
ip authentication key-chain eigrp
key
key chain
key-string
send-lifetime
To configure the percentage of bandwidth that may be used by Enhanced IGRP on an interface, use the ip bandwidth-percent eigrp interface configuration command. To restore the default value, use the no form of this command.
ip bandwidth-percent eigrp as-number percent
as-number | Autonomous system number. |
percent | Percent of bandwidth that Enhanced IGRP may use. |
50 percent
Interface configuration
This command first appeared in Cisco IOS Release 11.2.
Enhanced IGRP will use up to 50 percent of the bandwidth of a link, as defined by the bandwidth interface configuration command. This command may be used if some other fraction of the bandwidth is desired. Note that values greater than 100 percent may be configured; this may be useful if the bandwidth is set artificially low for other reasons.
The following example allows Enhanced IGRP to use up to 75 percent (42 kbps) of a 56-kbps serial link in autonomous system 209:
interface serial 0
bandwidth 56
ip bandwidth-percent eigrp 209 75
You can use the master indexes or search online to find documentation of related commands.
bandwidth
To configure the hello interval for the Enhanced IGRP routing process designated by an autonomous system number, use the ip hello-interval eigrp interface configuration command. To restore the default value, use the no form of this command.
ip hello-interval eigrp autonomous-system-number seconds
autonomous-system-number | Autonomous system number. |
seconds | Hello interval, in seconds. |
For low-speed, NBMA networks: 60 seconds
For all other networks: 5 seconds
Interface configuration
This command first appeared in Cisco IOS Release 10.0.
The default of 60 seconds applies only to low-speed, nonbroadcast, multiaccess (NBMA) media. Low speed is considered to be a rate of T1 or slower, as specified with the bandwidth interface configuration command. Note that for the purposes of Enhanced IGRP, Frame Relay and SMDS networks may or may not be considered to be NBMA. These networks are considered NBMA if the interface has not been configured to use physical multicasting; otherwise, they are considered not to be NBMA.
The following example sets the hello interval for Ethernet interface 0 to 10 seconds:
interface ethernet 0
ip hello-interval eigrp 109 10
You can use the master indexes or search online to find documentation of related commands.
To configure the hold time for a particular Enhanced IGRP routing process designated by the autonomous system number, use the ip hold-time eigrp interface configuration command. To restore the default value, use the no form of this command.
ip hold-time eigrp autonomous-system-number seconds
autonomous-system-number | Autonomous system number. |
seconds | Hold time, in seconds. |
For low-speed, NBMA networks: 180 seconds
For all other networks: 15 seconds
Interface configuration
This command first appeared in Cisco IOS Release 10.0.
On very congested and large networks, the default hold time might not be sufficient time for all routers and access servers to receive hello packets from their neighbors. In this case, you may want to increase the hold time.
We recommend that the hold time be at least three times the hello interval. If a router does not receive a hello packet within the specified hold time, routes through this router are considered unavailable.
Increasing the hold time delays route convergence across the network.
The default of 180 seconds hold time and 60 seconds hello interval apply only to low-speed, nonbroadcast, multiaccess (NBMA) media. Low speed is considered to be a rate of T1 or slower, as specified with the bandwidth interface configuration command.
The following example sets the hold time for Ethernet interface 0 to 40 seconds:
interface ethernet 0
ip hold-time eigrp 109 40
You can use the master indexes or search online to find documentation of related commands.
To enable Enhanced IGRP split horizon, use the ip split-horizon eigrp interface configuration command. To disable split horizon, use the no form of this command.
ip split-horizon eigrp autonomous-system-number
autonomous-system-number | Autonomous system number. |
Enabled
Interface configuration
This command first appeared in Cisco IOS Release 10.0.
For networks that include links over X.25 PSNs, you can use the neighbor router configuration command to defeat the split horizon feature. As an alternative, you can explicitly specify the no ip split-horizon eigrp command in your configuration. However, if you do so, you must similarly disable split horizon for all routers and access servers in any relevant multicast groups on that network.
The following example disables split horizon on a serial link connected to an X.25 network:
interface serial 0
encapsulation x25
no ip split-horizon eigrp
You can use the master indexes or search online to find documentation of related commands.
ip split-horizon
neighbor (IGRP, RIP)
To configure a summary aggregate address for a specified interface, use the ip summary-address eigrp interface configuration command. To disable a configuration, use the no form of this command.
ip summary-address eigrp autonomous-system-number address mask
autonomous-system-number | Autonomous system number. |
address | IP summary aggregate address to apply to an interface. |
mask | Subnet mask. |
No summary aggregate addresses are predefined.
Interface configuration
This command first appeared in Cisco IOS Release 10.0.
Enhanced IGRP summary routes are given an administrative distance value of 5. You cannot configure this value.
The following example sets the IP summary aggregate address for Ethernet interface 0:
interface ethernet 0
ip summary-address eigrp 109 192.1.0.0 255.255.0.0
You can use the master indexes or search online to find documentation of related commands.
To allow the tuning of the IGRP or Enhanced IGRP metric calculations, use the metric weights router configuration command. To reset the values to their defaults, use the no form of this command.
metric weights tos k1 k2 k3 k4 k5
tos | Type of service. Currently, it must always be zero. |
k1-k5 | Constants that convert an IGRP or enhanced IGRP metric vector into a scalar quantity. |
tos: 0
k1: 1
k2: 0
k3: 1
k4: 0
k5: 0
Router configuration
This command first appeared in Cisco IOS Release 10.0.
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 or Enhanced 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 2.56 ¥ 1012. The range is from a 1200-bps line to 10 terabits per second.
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 32-bit field, in increments of 39.1 nanoseconds. This gives a range of 1 (39.1 nanoseconds) to hexadecimal FFFFFFFF (decimal 4,294,967,040 nanoseconds). A delay of all ones (that is, a delay of hexadecimal FFFFFFFF) indicates that the network is unreachable.
Table 39 lists the default values used for several common media.
| Media Type | Delay | Bandwidth |
|---|---|---|
Satellite | 5120 (2 seconds) | 5120 (500 Mbits) |
Ethernet | 25600 (1 ms) | 256000 (10 Mbits) |
1.544 Mbps | 512000 (20,000 ms) | 1,657,856 bits |
64 kbps | 512000 (20,000 ms) | 40,000,000 bits |
56 kbps | 512000 (20,000 ms) | 45,714,176 bits |
10 kbps | 512000 (20,000 ms) | 256,000,000 bits |
1 kbps | 512000 (20,000 ms) | 2,560,000,000 bits |
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.
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
You can use the master indexes or search online to find documentation of related commands.
bandwidth
delay
metric holddown
metric maximum-hops
To specify a list of networks for the Enhanced IGRP routing process, use this form of the network router configuration command. To remove an entry, use the no form of this command.
network network-number
network-number | IP address of the directly connected networks. |
No networks are specified.
Router configuration
This command first appeared in Cisco IOS Release 10.0.
The network number specified must not contain any subnet information. There is no limit to the number of network commands you can use on the router.
IGRP or Enhanced 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 or Enhanced IGRP update.
The following example configures a router for IGRP and assigns autonomous system 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
You can use the master indexes or search online to find documentation of related commands.
router igrp
router eigrp
To add an offset to incoming and outgoing metrics to routes learned via Enhanced IGRP, use the offset-list router configuration command. To remove an offset list, use the no form of this command.
offset-list {access-list-number | name} {in | out} offset [type number]
access-list-number | name | Standard access list number or name to be applied. Access list number 0 indicates all access lists. If offset is 0, no action is taken. For IGRP, the offset is added to the delay component only. |
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 0, no action is taken. |
type | (Optional) Interface type to which the offset-list is applied. |
number | (Optional) Interface number to which the offset-list is applied. |
Disabled
Router configuration
This command first appeared in Cisco IOS Release 10.0. The type and number arguments first appeared in Cisco IOS Release 10.3. The name argument first appeared in Cisco IOS Release 11.2.
The offset value is added to the routing metric. An offset-list with an interface type and interface number is considered extended and takes precedence over an offset-list that is not extended. Therefore, if an entry passes the extended offset-list and the normal offset-list, the extended offset-list's offset is added to the metric.
In the following example, the router applies an offset of 10 to the router's delay component only to access list 21:
offset-list 21 out 10
In the following example, the router applies an offset of 10 to routes learned from Ethernet interface 0:
offset-list 21 in 10 ethernet 0
To configure the Enhanced IGRP routing process, use the router eigrp global configuration command. To shut down a routing process, use the no form of this command.
router eigrp autonomous-system
autonomous-system | Autonomous system number that identifies the routes to the other Enhanced IGRP routers. It is also used to tag the routing information. |
Disabled
Global configuration
This command first appeared in Cisco IOS Release 10.0.
The following example shows how to configure an Enhanced IGRP routing process and assign process number 109:
router eigrp 109
You can use the master indexes or search online to find documentation of related commands.
network (IGRP and Enhanced IGRP)
To set the metric value for IP Enhanced IGRP in a route-map, use the set metric route-map configuration command. To return to the default metric value, use the no form of this command.
set metric bandwidth delay reliability loading mtu
bandwidth | Metric value or IGRP bandwidth of the route in kilobits per second. It can be in the range 0 to 4294967295. |
delay | Route delay in tens of microseconds. It can be in the range 0 to 4294967295. |
reliability | Likelihood of successful packet transmission expressed as a number between 0 and 255. The value 255 means 100 percent reliability; 0 means no reliability. |
loading | Effective bandwidth of the route expressed as a number from 0 to 255 (255 is 100 percent loading). |
mtu | Minimum maximum transmission unit (MTU) size of the route in bytes. It can be in the range 0 to 4294967295. |
No metric will be set in the route-map.
Route-map configuration
This command first appeared in Cisco IOS Release 10.0.
Use the route-map global configuration command, and the match and set route-map configuration commands, 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 command. 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.
In the following example, the bandwidth is set to 10,000, the delay is set to 10, the reliability is set to 255, the loading is set to 1, and the MTU is set to 1500:
set metric 10000 10 255 1 1500
To display information about interfaces configured for Enhanced IGRP, use the show ip eigrp interfaces EXEC command.
show ip eigrp interfaces [type number] [as-number]
type | (Optional) Interface type. |
number | (Optional) Interface number. |
as-number | (Optional) Autonomous system number. |
EXEC
This command first appeared in Cisco IOS Release 11.2.
Use the show ip eigrp interfaces command to determine on which interfaces Enhanced IGRP is active, and to find out information about Enhanced IGRP relating to those interfaces.
If an interface is specified, only that interface is displayed. Otherwise, all interfaces on which Enhanced IGRP is running are displayed.
If an autonomous system is specified, only the routing process for the specified autonomous system is displayed. Otherwise, all Enhanced IGRP processes are displayed.
The following is sample output from the show ip eigrp interfaces command:
Router> show ip eigrp interfaces
IP EIGRP interfaces for process 109
Xmit Queue Mean Pacing Time Multicast Pending
Interface Peers Un/Reliable SRTT Un/Reliable Flow Timer Routes
Di0 0 0/0 0 11/434 0 0
Et0 1 0/0 337 0/10 0 0
SE0:1.16 1 0/0 10 1/63 103 0
Tu0 1 0/0 330 0/16 0 0
Table 40 describes the fields in the display.
| Field | Description |
|---|---|
Interface | Interface over which Enhanced IGRP is configured. |
Peers | Number of directly connected Enhanced IGRP neighbors. |
Xmit Queue Un/Reliable | Number of packets remaining in the Unreliable and Reliable transmit queues. |
Mean SRTT | Mean SRTT in seconds. |
Pacing Time Un/Reliable | Pacing time used to determine when Enhanced IGRP packets should be sent out the interface (Unreliable and Reliable packets). |
Multicast Flow Timer | Maximum number of seconds in which router will send multicast Enhanced IGRP packets. |
Pending Routes | Number of routes in the packets sitting in the transmit queue waiting to be sent. |
You can use the master indexes or search online to find documentation of related commands.
show ip eigrp neighbors
To display the neighbors discovered by Enhanced IGRP, use the show ip eigrp neighbors EXEC command.
show ip eigrp neighbors [type number]
type | (Optional) Interface type. |
number | (Optional) Interface number. |
EXEC
This command first appeared in Cisco IOS Release 10.3.
Use the show ip eigrp neighbors command to determine when neighbors become active and inactive. It is also useful for debugging certain types of transport problems.
The following is sample output from the show ip eigrp neighbors command:
Router# show ip eigrp neighbors
IP-EIGRP Neighbors for process 77
Address Interface Holdtime Uptime Q Seq SRTT RTO
(secs) (h:m:s) Count Num (ms) (ms)
160.89.81.28 Ethernet1 13 0:00:41 0 11 4 20
160.89.80.28 Ethernet0 14 0:02:01 0 10 12 24
160.89.80.31 Ethernet0 12 0:02:02 0 4 5 20
Table 41 explains the fields in the output.
| Field | Description |
|---|---|
process 77 | Autonomous system number specified in the router configuration command. |
Address | IP address of the enhanced IGRP peer. |
Interface | Interface on which the router is receiving hello packets from the peer. |
Holdtime | Length of time, in seconds, that the Cisco IOS software will wait to hear from the peer before declaring it down. If the peer is using the default hold time, this number will be less than 15. If the peer configures a nondefault hold time, it will be reflected here. |
Uptime | Elapsed time, in hours, minutes, and seconds, since the local router first heard from this neighbor. |
Q Count | Number of Enhanced IGRP packets (Update, Query, and Reply) that the software is waiting to send. |
Seq Num | Sequence number of the last update, query, or reply packet that was received from this neighbor. |
SRTT | Smooth round-trip time. This is the number of milliseconds it takes for an Enhanced IGRP packet to be sent to this neighbor and for the local router to receive an acknowledgment of that packet. |
RTO | Retransmission timeout, in milliseconds. This is the amount of time the software waits before retransmitting a packet from the retransmission queue to a neighbor. |
To display the Enhanced IGRP topology table, use the show ip eigrp topology EXEC command.
show ip eigrp topology [autonomous-system-number | [[ip-address] mask]]
autonomous-system-number | (Optional) Autonomous system number. |
ip-address | (Optional) IP address. When specified with a mask, a detailed description of the entry is provided. |
mask | (Optional) Subnet mask. |
EXEC
This command first appeared in Cisco IOS Release 10.0.
Use the show ip eigrp topology command to determine Diffusing Update Algorithm (DUAL) states and to debug possible DUAL problems.
The following is sample output from the show ip eigrp topology command:
Router# show ip eigrp topology
IP-EIGRP Topology Table for process 77
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
r - Reply status
P 160.89.90.0 255.255.255.0, 2 successors, FD is 0
via 160.89.80.28 (46251776/46226176), Ethernet0
via 160.89.81.28 (46251776/46226176), Ethernet1
via 160.89.80.31 (46277376/46251776), Ethernet0
P 160.89.81.0 255.255.255.0, 1 successors, FD is 307200
via Connected, Ethernet1
via 160.89.81.28 (307200/281600), Ethernet1
via 160.89.80.28 (307200/281600), Ethernet0
via 160.89.80.31 (332800/307200), Ethernet0
Table 42 explains the fields in the output.
| Field | Description |
|---|---|
Codes | State of this topology table entry. Passive and Active refer to the Enhanced IGRP state with respect to this destination; Update, Query, and Reply refer to the type of packet that is being sent. |
P - Passive | No Enhanced IGRP computations are being performed for this destination. |
A - Active | Enhanced IGRP computations are being performed for this destination. |
U - Update | Indicates that an update packet was sent to this destination. |
Q - Query | Indicates that a query packet was sent to this destination. |
R - Reply | Indicates that a reply packet was sent to this destination. |
r - Reply status | Flag that is set when after the software has sent a query and is waiting for a reply. |
160.89.90.0 and so on | Destination IP network number. |
255.255.255.0 | Destination subnet mask. |
successors | Number of successors. This number corresponds to the number of next hops in the IP routing table. |
FD | Feasible distance. This value is used in the feasibility condition check. If the neighbor's reported distance (the metric after the slash) is less than the feasible distance, the feasibility condition is met and that path is a feasible successor. Once the software determines it has a feasible successor, it does not have to send a query for that destination. |
replies | Number of replies that are still outstanding (have not been received) with respect to this destination. This information appears only when the destination is in Active state. |
state | Exact Enhanced IGRP state that this destination is in. It can be the number 0, 1, 2, or 3. This information appears only when the destination is Active. |
via | IP address of the peer who told the software about this destination. The first N of these entries, where N is the number of successors, are the current successors. The remaining entries on the list are feasible successors. |
(46251776/46226176) | The first number is the Enhanced IGRP metric that represents the cost to the destination. The second number is the Enhanced IGRP metric that this peer advertised. |
Ethernet0 | Interface from which this information was learned. |
To display the number of Enhanced IGRP packets sent and received, use the show ip eigrp traffic EXEC command.
show ip eigrp traffic [autonomous-system-number]
autonomous-system-number | (Optional) Autonomous system number. |
EXEC
This command first appeared in Cisco IOS Release 10.0.
The following is sample output from the show ip eigrp traffic command:
Router# show ip eigrp traffic
IP-EIGRP Traffic Statistics for process 77
Hellos sent/received: 218/205
Updates sent/received: 7/23
Queries sent/received: 2/0
Replies sent/received: 0/2
Acks sent/received: 21/14
Table 43 describes the fields that might be shown in the display.
| Field | Description |
|---|---|
process 77 | Autonomous system number specified in the ip router command. |
Hellos sent/received | Number of hello packets that were sent and received. |
Updates sent/received | Number of update packets that were sent and received. |
Queries sent/received | Number of query packets that were sent and received. |
Replies sent/received | Number of reply packets that were sent and received. |
Acks sent/received | Number of acknowledgment packets that were sent and received. |
balanced | Distributes traffic proportionately to the ratios of the metrics. |
min | Uses routes that have minimum costs. |
Traffic is distributed proportionately to the ratios of the metrics.
Router configuration
This command first appeared in Cisco IOS Release 10.0.
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 Cisco IOS software to only divide traffic among the routes with the best metric. Other routes will remain in the routing table, but will receive no traffic.
In the following example, only routes of minimum cost will be used:
router igrp 5
traffic-share min
To control load balancing in an Enhanced IGRP-based internetwork, use the variance router configuration command. To reset the variance to the default value, use the no form of this command.
variance multiplier
multiplier | Metric value used for load balancing. It can be a value from 1 to 128. The default is 1, which means equal-cost load balancing. |
1 (equal-cost load balancing)
Router configuration
This command first appeared in Cisco IOS Release 10.0.
Setting a variance value lets the Cisco IOS software 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.
The following example sets a variance value of 4:
router igrp 109
variance 4
Posted: Wed Nov 15 16:06:12 PST 2000
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