3Com S7902E, Руководство по настройке

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After route reflection is disabled between clients, routes can still be reflected between a client and a
non-client.
Confederation
Confederation is another method to deal with growing iBGP connections in ASs. It splits an AS into
multiple sub-ASs. In each sub-AS, iBGP peers are fully meshed, and intra-confederation eBGP
connections are established between sub-ASs, as shown below:
Figure 1-15 Confederation network diagram
From the perspective of a non-confederation BGP speaker, it needs not know sub-ASs in the
confederation. The ID of the confederation is the number of the AS. In the above figure, AS 200 is the
confederation ID.
The deficiency of confederation is: when changing an AS into a confederation, you need to reconfigure
your routers, and the topology will be changed.
In large-scale BGP networks, both route reflector and confederation can be used.
BGP GR
For GR (Graceful Restart) information, refer to GR Configuration in the High Availability Volume .
1) To establish a BGP session with a peer, a BGP GR Restarter sends an Open message with GR
capability to the peer.