From: trouse@cisco.com
Date: Fri Apr 02 2004 - 18:59:42 GMT-3
Advanced Route Reflectors Example
http://www.cisco.com/univercd/cc/td/doc/cisintwk/ics/icsbgp4.htm#7236
In Figure 12-30, Routers A, B, and C form a cluster, and Router C is the route reflector. Routers D, E, and F form a second cluster, of which Router D is the route reflector. Router G forms a third cluster. Note that Routers C, D, and G are fully meshed and that the routers within a cluster are not fully meshed.
When a route reflector in Figure 12-30 receives an update, it takes the following actions, depending on the type of peer that sent the update:
* Update from a nonclient peerSend the update to all clients in the cluster.
* Update from a client peerSend the update to all nonclient peers and to all client peers.
* Update from EBGP peerSend the update to all nonclient peers and to all client peers.
The following configurations establish the route reflectors in AS 100:
!Router C
router bgp 100
neighbor 1.1.1.1 remote-as 100
neighbor 1.1.1.1 route-reflector-client
neighbor 2.2.2.2 remote-as 100
neighbor 2.2.2.2 route-reflector-client
neighbor 7.7.7.7 remote-as 100
neighbor 4.4.4.4 remote-as 100
neighbor 8.8.8.8 remote-as 200
!Router B
router bgp 100
neighbor 3.3.3.3 remote-as 100
neighbor 12.12.12.12 remote-as 300
!Router D
router bgp 100
neighbor 5.5.5.5 remote-as 100
neighbor 5.5.5.5 route-reflector-client
neighbor 6.6.6.6 remote-as 100
neighbor 6.6.6.6 route-reflector-client
neighbor 3.3.3.3 remote-as 100
neighbor 7.7.7.7 remote-as 100
THIS IS WHAT I AM NOT UNDERSTANDING. CAN SOMEONE HELP CLARIFY> ARE THEY
REFERRING TO ROUTEMAPS ON THE CLIENT OR THE RR. IF CLIENT, What if the client
has an IBGP peer other than the RR. I know it is not a good design to do that but I have seen scenerios that ask for it, and we know the LAB is not a best practice lab.
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If a set clause is used to modify an attribute, a routing loop may occur when the IBGP-learned routes are reflected. BGP automatically prevents the set clause of outgoing route maps from affecting routes reflected to IBGP peers. Another automatic restriction concerns the neighbor next-hop-self router configuration command. Because the next hop of reflected routes should not be changed, the neighbor next-hop-self command only affects the next hop of EBGP-learned routes when used with route reflectors.
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