3Com MSR 50 Series Configuration Manual page 838

838 C 56: BGP C
HAPTER ONFIGURATION
n
BGP GR
n
When clients of a route reflector are fully meshed, route reflection is unnecessary
because it consumes more bandwidth resources. The system supports using
related commands to disable route reflection in this case.
After route reflection is disabled between clients, routes between clients and
non-clients can still be reflected.
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 EBGP connections are established between sub ASs, as shown below:
Figure 245 Confederation network diagram
EBGP
AS 100
AS 200
From the perspective of a non-confederation 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.
For GR (Graceful Restart) information, refer to
1 To establish a BGP session with a peer, a BGP GR Restarter sends an OPEN message
with GR capability to the peer.
2 Upon receipt of this message, the peer is aware that the sending router is capable
of Graceful Restart, and sends an OPEN message with GR Capability to the GR
Restarter to establish a GR session. If neither party has the GR capability, the
session established between them will not be GR capable.
AS 65002
EBGP
EBGP
IBGP
IBGP
IBGP
AS 65003
AS 65004
"GR Overview" on page 1957.