System information

Troubleshooting TCP/IP

Book Title

7-116

RIP/IGRP: Routes Missing from Routing Table

Symptom: Routes are missing from the routing table. Hosts on one network cannot access hosts on

a different network. Error messages stating “host or destination unreachable” are generated.

The problem might be occurring in an internetwork running only RIP or IGRP, or a combination of

the two.

Table 7-9 outlines the problems that might cause this symptom and describes solutions to those

problems.

Table 7-9 RIP/IGRP: Routes Missing from Routing Table

Possible Problem Solution

Misconﬁgured or

missing network router

conﬁguration command

Step 1 Use the show running-conﬁg privileged exec command to view the

router conﬁguration.

Step 2 Make sure that a network router conﬁguration command is speciﬁed for

every network to which a router interface belongs.

For example, if the IP address of one interface is 192.168.52.42, and the

IP address of another interface is 108.168.54.10, enter the following

commands to enable RIP on the interfaces:

c4500(config)#router rip

c4500(config-router)#network 192.168.52.0

c4500(config-router)#network 108.168.0.0

Make sure the correct process IDs, addresses, and other variables are properly

speciﬁed for the routing protocol you are using. For more information, consult the

Cisco IOS conﬁguration guides and command references.

Misconﬁgured route ﬁltering

Step 1 Use the show running-conﬁg command to check suspect routers.

Step 2 See if any distribute-list in or distribute-list out router conﬁguration

commands are conﬁgured on the router.

The distribute-list in command ﬁlters speciﬁc information in routing

updates received by a router. The distribute-list out command prevents a

router from including speciﬁc information in routing updates that it

transmits.

The information that is ﬁltered is speciﬁed with an access list.