Configuring Confederations

Configuring Confederations
When configuring confederations, you first need to enable BGP on the devices. The router
bgp member-AS-number command will accomplish this. After BGP has been enabled, you
will be required to configure all BGP speakers participating in the confederation with the confederation
ID. The following command can be used in router configuration mode for BGP to
accomplish this:
bgp confederation identifier confederation-ID
confederation-ID - the AS number you want advertised to all BGP peers
outside of the confederation.
After successfully configuring the confederation ID on all BGP speakers participating in the
confederation, you need to specify on each of these BGP speakers what the member-AS numbers
are to all member-ASs in the confederation. This is done so the BGP speaker can determine
whether its BGP peer is part of the confederation. The following command needs to be entered
in router configuration mode:
bgp confederation peers AS-number […AS-number]
AS-number […AS-number] - all of the member-AS numbers of all of the
member-ASes participating in the confederation. This does not include
the local member-AS the BGP speaker is part of.
This command, along with the normal commands used to configure BGP, is all that’s needed
to configure confederations. There are a couple of rules you need to keep in mind when configuring
confederations:
 When configuring neighbor statements for BGP peers in the confederation, use their
respective member-AS numbers.
 When configuring a BGP speaker in a neighboring AS to a peer with a BGP speaker in the
confederation, use the confederation ID in the neighbor statement.
 When enabling BGP on a BGP speaker in a member-AS, use the member-AS number.
We will configure the BGP network depicted in Figure 9.6. You need to use the loopback
interfaces of all routers for the BGP sessions. You do not need to take care of the IGP. We will
assume it is already configured correctly and includes the loopback interfaces:
R1 Lo0-1.1.1.1
R2 Lo0-2.2.2.2
R3 Lo0-3.3.3.3
R4 Lo0-4.4.4.4
R5 Lo0-5.5.5.5
R6 Lo0-6.6.6.6
R7 Lo0-7.7.7.7