User's Manual

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match
community-list-name
Configure rules of matching.
router bgp
autonomous-system
Enter into router configuration mode
neighbor
{ip-address | peer-group-name}
route-
map
route-map-name {
in | out
}
Apply route-map.
For examples of using community attributes, please refer to “Examples of route-map using BGP community
attribute”.
4. Configure autonomous system confederation
The way to reduce the number of IBGP connections is to divide an AS into several sub-AS, then form them
into an autonomous system confederation. From the external perspective, the confederation looks like an AS.
In the confederation, each sub-AS is full-mesh inside, and has connections with other sub-ASs in the same
confederation. Even if there are EBGP sessions between peers of different sub-ASs, they may still exchange
routing selection information like IBGP peers. Concretely speaking, it is saving the nexthop, MED and local
precedence information.
To configure a BGP autonomous system confederation, you should designate the confederation identifier. The
confederation identifier is an AS number, from an external perspective, the confederation is just like a single
AS with AS number being the confederation identifier.
Use the following BGP configuration command to configure confederation identifier of the autonomous system:
Command Purpose
bgp confederation0 identifier
autonomous-system Configure the confederation identifier of the
autonomous system.
In order to designate the autonomous system number belonging to autonomous system confederation, use
the following BGP configuration command:
Command Purpose
bgp confederation peers autonomous-system
[
autonomous-system ...
]
Designate the AS belongs to the confederation
of autonomous system.
For examples of autonomous system confederation, please refer to “examples of BGP autonomous system
confederation”.
5. Configure route reflector
Another method to reduce the number of IBGP connections instead of configuring autonomous system
confederation is to configure route reflector.
The internal peers of the route reflector are divided into two groups: client peers and all other routers (non-
client peers). The route reflector reflects the routes between the two groups; the route reflector and its client
peers form a cluster. Non-client peers must be full-mesh connected, but client peers need not. The clients in
the cluster do not communicate with IBGP speakers outside the cluster.
When route reflector receives routing information, it completes the following tasks:
Broadcast the routes from external BGP speaker to all clents and non-client peers.
Broadcast the routes from non-client to all clents.
Broadcast the routes from the clients to all clients and non-client peers. So, the client peers
need not be full-mesh-conneted.
Use the following router configuration command to configure the local router as the reflector and designate