System information

Troubleshooting TCP/IP 7-133

BGP: Routers Not Advertising Routes

Symptom: BGP routers are not advertising routes. Routing updates from a BGP router do not

contain information about certain network destinations that should be advertised.

Table 7-17 outlines the problems that might cause this symptom and describes solutions to those

problems.

Table 7-17 BGP: Routers Not Advertising Routes

Possible Problem Solution

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 that the BGP router should advertise (these networks need

not be directly connected).

For example, if you want the BGP router to advertise networks

192.168.52.0 and 108.168.0.0, enter the following commands to have the

router include those networks in its routing updates:

c4500(config)#router bgp 100

c4500(config-router)#network 192.168.52.0

c4500(config-router)#network 108.168.0.0

Interior gateway protocol (such

as RIP, IGRP, OSPF, and so on)

routing problem

Step 1 Check for other routing protocol problems to be sure that BGP is getting

routing information from any interior gateway protocols running in the

internetwork.

For example, if there is a problem with RIP routing, it might affect the

operation of BGP. BGP routers might not have any information about

certain networks, making it impossible to advertise routing information

about certain networks conﬁgured in BGP.

Step 2 Isolate and troubleshoot interior gateway protocol problems before

troubleshooting BGP. See the appropriate sections in this chapter for

information speciﬁc to the protocols you are running. As a workaround,

you can conﬁgure static BGP routes, but routing is not dynamic in this

case.