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What is RR in BGP?
Route reflectors (RR) are one method to get rid of the full-mesh of IBGP peers in your network. The other method is BGP confederations. The route reflector allows all IBGP speakers within your autonomous network to learn about the available routes without introducing loops.
Why do we need route reflector in BGP?
Route reflectors have the special BGP ability to readvertise routes learned from an internal peer to other internal peers. So rather than requiring all internal peers to be fully meshed with each other, route reflection requires only that the route reflector be fully meshed with all internal peers.
Should route reflectors peer with each other?
Because clients do not know they are clients, a route reflector can itself be a client of another route reflector. As a result, you can build “nested” route reflection clusters (see Figure 2-40). Although clients cannot peer with routers outside of their own cluster, they can peer with each other.
Why are RR’s bad for a BGP neighbor?
The problem we face with introducing RR’s is that an iBGP neighbor looses visibility to all the possible paths for prefix “P” as RR only sends the best path to the RR clients. The other impact is around multi-pathing. If there are 5 equal paths for a prefix “P” then ideally one would prefer to use all the five paths equally.
Which is better BGP add path or R1?
The path to 8.8.8.0/24 through R1 (1.1.1.1) is preferred to the path via R2 (1.1.1.2) because the IGP metric 2 is lower than 4 (Picture 3). Therefore, the RR router installs the 8.8.8.0/24 route via R1 into its routing table. As the BGP advertises only the best path, the path via R2 is not being advertised to the clients.
Can a BGP route be associated with the next hop?
Paths for which the NEXT_HOP is inaccessible. Be sure that there is an Interior Gateway Protocol (IGP) route to the NEXT_HOP that is associated with the path. Paths from an external BGP (eBGP) neighbor if the local autonomous system (AS) appears in the AS_PATH.
How does the BGP optimal route reflection work?
For the BGP Optimal Route Reflection to work properly, the RR must have a complete view of the network topology from the IGP perspective. Hence, network must run a link-state routing protocol (OSPF or IS-IS). Also, the border routers must be RR clients.