Route Reflectors

CD.

Route reflectors are a scalability feature in BGP networks that allow the reduction of the number of iBGP connections required between routers by introducing hierarchy in the iBGP topology. Here are the explanations for the two correct statements:

A. Routes received from nonclient peers are reflected to route reflector clients as well as nonclient peers.

Route reflectors are configured as a central point in the iBGP topology to which other routers connect as clients. The route reflector receives all iBGP routes from its clients and nonclients and reflects them to its clients. When a nonclient router sends an iBGP route to a route reflector, the route reflector reflects that route to its clients, including other route reflectors in the same cluster. The nonclient peers, however, don't receive the routes learned from other nonclient peers.

D. Routes received from a route reflector client is reflected to other clients and nonclient peers.

A route reflector client is a router that is configured to use a route reflector for iBGP updates. When a route reflector client sends an iBGP route to the route reflector, the route reflector reflects that route to its other clients and nonclient peers, including other route reflectors in the same cluster. This is how a route reflector distributes routes between clients in the iBGP topology.

The other statements are incorrect:

B. Routes received from nonclient peers are reflected to route reflector cluster as well as OSPF peers.

Route reflectors only reflect iBGP routes to other iBGP routers, including other route reflectors in the same cluster. OSPF is a different routing protocol, and its routers are not part of the iBGP topology.

C. If a router received an iBGP route with the originator-ID attribute set to its own router ID, the route is discarded.

The originator-ID attribute is a BGP attribute that is used to prevent routing loops in iBGP. If a router receives an iBGP route with the originator-ID attribute set to its own router ID, the route is not discarded but rather ignored, as it indicates that the router is the originator of the route.

E. If a route reflector receives a route with a cluster-list attribute containing a different cluster ID, the route is discarded.

The cluster-list attribute is used by route reflectors to prevent routing loops in iBGP. If a route reflector receives a route with a cluster-list attribute containing a different cluster ID, the route is not discarded but rather modified by adding its own cluster ID to the list before reflecting it to its clients. This modification ensures that the route does not loop back to the same cluster.