Problem: Configuration Mistakes-Cause: Failed to Configure IBGP Neighbor as a Route-Reflector Client

Problem: Configuration Mistakes ‚ Cause: Failed to Configure IBGP Neighbor as a Route-Reflector Client

Configuring route reflectors is fairly simple. In route-reflector BGP configuration, IBGP neighbors' peering addresses are listed as route-reflector clients ; however, a BGP operator inadvertently might configure an incorrect IBGP peering address as a route-reflector client.

Figure 15-27 shows that R1 is an RR. R8 and R2 are RRCs of R1.

Figure 15-27. Simple Route-Reflection Environment

Debugs and Verification

Example 15-59 shows the required configuration needed to make R1 an RR for R8 and R2. No additional configuration is needed in R8 and R2 to become RRCs other than just the normal IBGP configuration to peer with R1.

Example 15-59 Configuring R1 as a Route Reflector with R8 and R2 as Clients

 R1#  router bgp 109   no synchronization   neighbor 131.108.1.2 remote-as 109    neighbor 131.108.1.2 route-reflector-client    neighbor 206.56.89.1 remote-as 109   neighbor 206.56.89.1 route-reflector-client  

The neighbor IP address must be the same in the route-reflector-client statement as in the remote-as configuration. The Cisco IOS Software BGP parser detects the misconfigured RRC IP address if BGP does not have an IBGP neighbor configured with this address.

For example, if the BGP operator types in this command

 R1#  router bgp 109   neighbor 131.108.1.8 route-reflector-client  

Cisco IOS Software will immediately display an error:

 % Specify remote-as or peer-group commands first 

BGP detects that 131.108.1.8 is not configured as a neighbor, so it cannot be associated as an RRC.

Use the show ip bgp neighbor command, as demonstrated in Example 15-60, to verify that the neighbor is configured as an RRC.

Example 15-60 Verifying Neighbor Configuration as an RRC

 R1#  show ip bgp neighbor 131.108.1.2  BGP neighbor is  131.108.1.2  , remote AS 1, internal link Index 1, Offset 0, Mask 0x2   Route-Reflector Client 

Solution

A BGP operator accidentally might configure a different IP address in the RRC than is configured in the neighbor statement where the remote AS is configured. If this problem is detected , the IP address must be corrected.