BGP: Difference between revisions
→Route Reflector?www.accenture.com
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= Route Reflector?<ref>www.accenture.com</ref> =
*Any route received from an iBGP neighbor must not be advertised to any other iBGP neighbor.
*This requires all iBGP routers be connected in logical full mesh topology, which is not scalable.
Two solution possible:
BGP confederations
Route reflectors
*A route reflector is BGP router that is allowed to break the iBGP loop avoidance rule.
*Route reflectors can advertise updates received from an iBGP peer to another iBGP peer.
*This allow for building iBGP networks that scale easily.
*IBGP routers are divided into:
Route Reflectors
Route Reflector Clients
Non-Client Peers
*Routes received from:
Route-Reflector-client is reflected to other clients and non-client neighbors
Non-client neighbors are reflected to Route-Reflector-client neighbors only
*Sets the '''Originator-ID''' attribute in the reflected update if it is not already set.
*Adds the Cluster-ID to the Cluster-list attribute in the reflected update.
*RR reflects routes considered as best routes only.
*If more than one update is received for the same destination only the BGP best route is reflected.
*RR is not allowed to change any attributes of the reflected routes including the next-hop attribute.
*Loop Prevention:
If a router received an iBGP route with the Originator-ID attribute set to its own router-id, the route is discarded.
If a route reflector receives a route with a cluster-list attribute containing its cluster-id, the route is discarded.
*Config:
;RR1 router:
router bgp 100
neighbor 172.16.1.2 remote-as 100
neighbor 172.16.1.2 route-reflector-client
neighbor 172.16.1.2 description Client1
;Client1 router:
router bgp 100
neighbor 172.16.1.1 remote-as 100
neighbor 172.16.1.1 description RR1
network 11.1.1.1 mask 255.255.255.255 --> Route to be reflected
= Confederation =
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