Recall that BGP requires all iBGP peers to be fully meshed. RouteReflectors allow us to bypass this restriction. Fewer neighbor connections will result in less bandwidth and CPU usage.
Route-reflector clients form neighbor adjacencies with the route-reflector server. BGP updates will flow from the server to the clients, without the clients having to interact with each other.
Consider the above example. In AS 100, there are three BGP speakers. Normally, these iBGP peers must be fully-meshed. For example, RouterB would need a neighbor statement for both RouterA and RouterD.
As an alternative, RouterA can be configured as a route-reflector server. Both RouterB and RouterD would only need to peer with RouterA.
All route-reflector specific configuration takes place on the route reflector server.
Configuration
[Huawei]bgp 100
[Huawei-bgp]peer 10.1.1.2 as-number 100
[Huawei-bgp]peer 10.2.1.2 as-number 100
[Huawei-bgp]ipv4-family unicast
[Huawei-bgp]undo synchronization == we didn't need to execute this command as synchronization is disbled by default.
[Huawei-bgp]peer 10.1.1.2 enable
[Huawei-bgp]peer 10.1.1.2 reflect-client
[Huawei-bgp]peer 10.2.1.2 enable
[Huawei-bgp]peer 10.2.1.2 reflect-client
