Route reflection can be implemented in autonomous systems with a large internal BGP mesh to reduce the number of IBGP sessions required. One or more routers can be selected to act as focal points for internal BGP sessions. Several BGP speaking routers can peer with a route reflector. A route reflector forms peer connections to other route reflectors. A router assumes the role as a route reflector by configuring the cluster cluster-id command. No other command is required unless you want to disable reflection to specific peers.
If you configure the cluster command at the global level, then all subordinate groups and neighbors are members of the cluster. The route reflector cluster ID is expressed in dotted-decimal notation. The ID should be a significant topology-specific value. No other command is required unless you want to disable reflection to specific peers.
If a route reflector client is fully meshed, the disable-client-reflect command can be enabled to stop the route reflector from reflecting redundant route updates to a client.
The following example displays a route reflection configuration:
ALA-B>config>router>bgp# info
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cluster 0.0.0.100
group "Santa Clara"
local-address 10.0.0.103
neighbor 10.0.0.91
peer-as 100
exit
neighbor 10.0.0.92
peer-as 100
exit
neighbor 10.0.0.93
disable-client-reflect
peer-as 100
exit
exit
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ALA-B>config>router>bgp#