BGP Route Reflectors

A route reflector is a BGP router configured to forward routing updates to peers within the same AS. Route reflectors reduce the problems that are caused by fully meshed IBGP topologies. This is accomplished by lowering the number of IBGP neighbor relationships needed in an AS. BGP route reflectors alleviate the scalability problem of internal BGP (IBGP) full mesh topologies by reducing the number of IBGP sessions that must be configured between routers. They serve to tweak the BGP split horizon rule by permitting a BGP router, configured as a route reflector, to send out IBGP-learned routes to other IBGP neighbors. This change in behavior can be seen in Figure 9.2.

Figure 9.2. RouterB is configured as a route reflector to ...

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