Multiple route reflector cluster

FIGURE 9 . 4 Multiple route reflector cluster
We will use R1 and R2 as the route reflectors, and the client peers will be R3, R4, and R5.
Each of the route reflectors needs a peering session with each of the clients. The cluster ID we
will use is 1. When configuring iBGP, use the loopback interface address of each device for the
BGP session and turn off synchronization. The loopback interface information is as follows:
R1 Lo0-1.1.1.1
R2 Lo0-2.2.2.2
AS 100
R3 R4
R1 R2
R5
Overcoming Scalability Limitations of iBGP 291
R3 Lo0-3.3.3.3
R4 Lo0-4.4.4.4
R5 Lo0-5.5.5.5
The first task is to configure iBGP on each of the routers:
R1#conf t
Enter configuration commands, one per line. End with CNTL/Z.
R1(config)#router bgp 100
R1(config-router)#no synchronization
R1(config-router)#neighbor 2.2.2.2 remote-as 100
R1(config-router)#neighbor 2.2.2.2 update-source Lo0
R1(config-router)#neighbor 3.3.3.3 remote-as 100
R1(config-router)#neighbor 3.3.3.3 update-source Lo0
R1(config-router)#neighbor 4.4.4.4 remote-as 100
R1(config-router)#neighbor 4.4.4.4 update-source Lo0
R1(config-router)#neighbor 5.5.5.5 remote-as 100
R1(config-router)#neighbor 5.5.5.5 update-source Lo0
R1(config-router)#^Z
R1#
R2#conf t
Enter configuration commands, one per line. End with CNTL/Z.
R2(config)#router bgp 100
R2(config-router)#no synchronization
R2(config-router)#neighbor 1.1.1.1 remote-as 100
R2(config-router)#neighbor 1.1.1.1 update-source Lo0
R2(config-router)#neighbor 3.3.3.3 remote-as 100
R2(config-router)#neighbor 3.3.3.3 update-source Lo0
R2(config-router)#neighbor 4.4.4.4 remote-as 100
R2(config-router)#neighbor 4.4.4.4 update-source Lo0
R2(config-router)#neighbor 5.5.5.5 remote-as 100
R2(config-router)#neighbor 5.5.5.5 update-source Lo0
R2(config-router)#^Z
R2#
R3#conf t
Enter configuration commands, one per line. End with CNTL/Z.
R3(config)#router bgp 100
R3(config-router)#no synchronization
R3(config-router)#neighbor 1.1.1.1 remote-as 100
R3(config-router)#neighbor 1.1.1.1 update-source Lo0
292 Chapter 9  Advanced Border Gateway Protocol
R3(config-router)#neighbor 2.2.2.2 remote-as 100
R3(config-router)#neighbor 2.2.2.2 update-source Lo0
R3(config-router)#^Z
R3#
R4#conf t
Enter configuration commands, one per line. End with CNTL/Z.
R4(config)#router bgp 100
R4(config-router)#no synchronization
R4(config-router)#neighbor 1.1.1.1 remote-as 100
R4(config-router)#neighbor 1.1.1.1 update-source Lo0
R4(config-router)#neighbor 2.2.2.2 remote-as 100
R4(config-router)#neighbor 2.2.2.2 update-source Lo0
R4(config-router)#^Z
R4#
R5#conf t
Enter configuration commands, one per line. End with CNTL/Z.
R5(config)#router bgp 100
R5(config-router)#no synchronization
R5(config-router)#neighbor 1.1.1.1 remote-as 100
R5(config-router)#neighbor 1.1.1.1 update-source Lo0
R5(config-router)#neighbor 2.2.2.2 remote-as 100
R5(config-router)#neighbor 2.2.2.2 update-source Lo0
R5(config-router)#^Z
R5#
The route reflectors with the appropriate cluster ID need to be configured:
R1#conf t
Enter configuration commands, one per line. End with CNTL/Z.
R1(config)#router bgp 100
R1(config-router)#bgp cluster-id 1
R1(config-router)#neighbor 3.3.3.3 route-reflector-client
R1(config-router)#neighbor 4.4.4.4 route-reflector-client
R1(config-router)#neighbor 5.5.5.5 route-reflector-client
R1(config-router)#^Z
R1#
R2#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Overcoming Scalability Limitations of iBGP 293
R2(config)#router bgp 100
R2(config-router)#bgp cluster-id 1
R2(config-router)#neighbor 3.3.3.3 route-reflector-client
R2(config-router)#neighbor 4.4.4.4 route-reflector-client
R2(config-router)#neighbor 5.5.5.5 route-reflector-client
R2(config-router)#^Z
R2#
That’s all there is to route reflectors. They are not the hardest technology to implement, but
they can save you a tremendous amount of time when configuring a large iBGP network, not
to mention reducing the amount of network traffic, memory, and processor overhead needed
for BGP.
Let’s turn our focus to the other alternative to a fully meshed iBGP network: confederations.