Border Gateway Protocol - CCIE Routing and Switching Exam Certification Guide - page 451

Example 9-15 Route Reflector Configuration Example (Continued)
!
router bgp 100
neighbor 1.1.1.1 remote-as 100
neighbor 1.1.1.7 remote-as 100
!The configuration of Router E is:
interface loopback 0
ip address 1.1.1.5 255.255.255.255
!
router bgp 100
neighbor 1.1.1.2 remote-as 100
!The configuration of Router F is:
interface loopback 0
ip address 1.1.1.6 255.255.255.255
!
router bgp 100
neighbor 1.1.1.2 remote-as 100
!The configuration of Router G is:
interface loopback 0
ip address 1.1.1.7 255.255.255.255
!
router bgp 100
neighbor 1.1.1.1 remote-as 100
neighbor 1.1.1.2 remote-as 100
neighbor 1.1.1.3 remote-as 100
neighbor 1.1.1.3 route-reflector-client
neighbor 1.1.1.4 remote-as 100
neighbor 1.1.1.4 route-reflector-client
bgp cluster-id 10
Confederations
Another method to reduce the iBGP mesh within an AS is to use BGP confederations. With
confederations, the AS is divided into smaller, private autonomous systems, and the entire
group is assigned a confederation ID. The routers within each private AS are configured with
the full iBGP mesh. Each private AS is configured with eBGP to communicate with other semi-
autonomous systems in the confederation. Only the AS number of the confederation is seen by
external autonomous systems, and this number is configured with the bgp confederation
identifier command.
In Figure 9-10, a confederation divides the AS into two.