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Route Reflectors

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The router being used as the concentration router needs to have its normal

BGP configuration, neighbor statements, and routers configured as clients.
On the concentration router (the route reflector), we need to identify the cli-
ents using the neighbor <peer clients IP address> route-
reflector-client

command. You need not migrate all the routers that

you need to migrate to using route reflectors at once since non-route-
reflector BGP routers can co-exist with route reflectors within an AS.

The concentration router needs to have a peer connection with the other

BGP routers that are non-clients of route reflectors and the other route
reflectors in the AS. The route-reflector clients need only have a neighbor
statement to peer with the route reflector. Let's look at some of the terms you
need to know when configuring route reflectors:

Route reflector A router configured to be able to advertise the routes it
learns from iBGP peers.

Client A router that is not configured as a route reflector but will share
information with the routers configured as route reflectors. Two route
reflectors can be configured as clients.

Cluster The combination of the routers configured as route reflectors
and the clients.

Cluster ID Used when a cluster has more than one route reflector, the
cluster ID allows route reflectors to recognize updates from other route
reflectors in the same cluster. A cluster that has a single route reflector is
identified by the Router ID of the route reflector.

The route reflector creates the ORIGINATOR_ID BGP attribute. This attribute is

used to carry the Router ID of the router that originated route information in

the local AS. This allows the originator to know if it receives back any infor-

mation it sent out. For more information on the ORIGINATOR_ID attribute, see

Chapter 7, "BGP's Basic Components."

Configuring a Route Reflector

When you configure route reflectors, you must configure them one at a time
and then configure the clients. Make sure that the routes propagate cor-
rectly. Always remember that when you are trying to control BGP routes,

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