Cisco NCS 5500 Series

BGP Route Reflectors Reference
Figure 2: Three Fully Meshed iBGP Speakers, on page 138 illustrates a simple iBGP configuration with three
iBGP speakers (routers A, B, and C). Without route reflectors, when Router A receives a route from an external
neighbor, it must advertise it to both routers B and C. Routers B and C do not readvertise the iBGP learned
route to other iBGP speakers because the routers do not pass on routes learned from internal neighbors to
other internal neighbors, thus preventing a routing information loop.
Figure 2: 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 3: Simple BGP Model with a Route Reflector, on
page 139 , Router B is configured as a route reflector. When the route reflector receives routes advertised from
BGP Configuration Guide for Cisco NCS 5500 Series Routers, IOS XR Release 6.2.x
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Implementing BGP
Information about Implementing BGP