Cisco NCS 6000 Series Configuration Manual page 54

Implementing BGP
BGP Route Reflectors
Figure 3: Three Fully Meshed iBGP Speakers
With route reflectors, all iBGP speakers need not be fully meshed because there is a method to pass learned
routes to neighbors. In this model, an iBGP peer is configured to be a route reflector responsible for passing
iBGP learned routes to a set of iBGP neighbors. In Figure 4: Simple BGP Model with a Route Reflector, on
page 32 , Router B is configured as a route reflector. When the route reflector receives routes advertised from
Router A, it advertises them to Router C, and vice versa. This scheme eliminates the need for the iBGP session
between routers A and C.
Figure 4: Simple BGP Model with a Route Reflector
The internal peers of the route reflector are divided into two groups: client peers and all other routers in the
autonomous system (nonclient peers). A route reflector reflects routes between these two groups. The route
reflector and its client peers form a cluster. The nonclient peers must be fully meshed with each other, but the
Routing Configuration Guide for Cisco NCS 6000 Series Routers, IOS XR Release 6.4.x
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