3.7.e Implement and troubleshoot scalability


3.7.e [ii] Confederations



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this is a topology i built this morning to illustrate a point about configuring confederations…

in the quick review for ccie r&s the steps for configurations follow:

Step 1.     Enable BGP using the member AS number.
Step 2.     Configure the confederation identifier using the bgp confederation identifier command.
Step 3.     Configure fully meshed iBGP sub-AS neighbor relationships using the sub-AS number as the remote AS number (ASN) for all internal iBGP peers.
Step 4.     Configure other neighbors within the same parent AS by specifying their sub-AS number as the remote AS number; other confederation peers from different sub-ASs must also be identified as external confederation peers using the bgp confederation peers command.

that is an awful way of putting it… think of the confederation as the grand AS and the peering relationships between the ibgp routers as bgp peering processes… 65001, the ebgp neighbor will peer with the confederation id, while the ibgp routers peer with other ibgp processes…

r1#sh run | b router
router bgp 2
bgp confederation identifier 1
bgp confederation peers 3
network mask
neighbor remote-as 2
neighbor remote-as 3
neighbor remote-as 65001

the bgp confederation peers are not the amount of peers, but rather the peer’s neighbor process..

65001(config-router)#do sh ip bgp | b Net
Network          Next Hop            Metric LocPrf Weight Path
*                              0 1 i
*>                         0             0 1 i
*                0             0 1 i
*>                                       0 1 i
*                              0 1 i
*>                                       0 1 i
*                              0 1 i
*>                                       0 1 i

the confederation is the umbrella…