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Implementing BGP on Cisco IOS XR Software
Configuration Examples for Implementing BGP on Cisco IOS XR Software
RC-78
Cisco IOS XR Routing Configuration Guide
BGP Neighbor Configuration: Example
The following example shows how BGP neighbors on an autonomous system are configured to share
information. In the example, a BGP router is assigned to autonomous system 109, and two networks are
listed as originating in the autonomous system. Then the addresses of three remote routers (and their
autonomous systems) are listed. The router being configured shares information about networks
131.108.0.0 and 192.31.7.0 with the neighbor routers. The first router listed is in a different autonomous
system; the second neighbor and remote-as commands specify an internal neighbor (with the same
autonomous system number) at address 131.108.234.2; and the third neighbor and remote-as
commands specify a neighbor on a different autonomous system.
router bgp 109
network 131.108.0.0
network 192.31.7.0
neighbor 131.108.200.1
remote-as 167
neighbor 131.108.234.2
remote-as 109
neighbor 150.136.64.19
remote-as 99
BGP Confederation: Example
The following is a sample configuration that shows several peers in a confederation. The confederation
consists of three internal autonomous systems with autonomous system numbers 6001, 6002, and 6003.
To the BGP speakers outside the confederation, the confederation looks like a normal autonomous
system with autonomous system number 666 (specified using the bgp confederation identifier
command).
In a BGP speaker in autonomous system 6001, the bgp confederation peers command marks the peers
from autonomous systems 6002 and 6003 as special eBGP peers. Hence, peers 171.69.232.55 and
171.69.232.56 get the local preference, next hop, and MED unmodified in the updates. The router at
160.69.69.1 is a normal eBGP speaker and the updates received by it from this peer are just like a normal
eBGP update from a peer in autonomous system 666.
router bgp 6001
bgp confederation identifier 666
bgp confederation peers 6002 6003
neighbor 171.69.232.55
remote-as 6002
neighbor 171.69.232.56
remote-as 6003
neighbor 160.69.69.1
remote-as 777
In a BGP speaker in autonomous system 6002, the peers from autonomous systems 6001 and 6003 are
configured as special eBGP peers. Peer 170.70.70.1 is a normal iBGP peer and peer 199.99.99.2 is a
normal eBGP peer from autonomous system 700.
router bgp 6002
bgp confederation identifier 666
bgp confederation peers 6001 6003
neighbor 170.70.70.1
remote-as 6002
neighbor 171.69.232.57
remote-as 6001
neighbor 171.69.232.56
remote-as 6003