Cisco Systems 78-11741-02 manual BGP Confederation Examples, IPC-344

Configuring BGP

BGP Configuration Examples

To conditionally advertise a set of routes, use the following commands in router configuration mode:

ip prefix-list BLUE permit 172.16.0.0 ip prefix-list RED permit 192.168.7.0

!

route-map map1-name permit 10 match ip address prefix-list BLUE

!

route-map map2-name permit 10 match ip address prefix-list RED

!

router bgp 100

neighbor 10.89.2.33 remote-as 2051

neighbor 10.89.2.33 advertise-map map1-name non-exist-map map2-name

!

BGP Confederation Examples

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 60000 (specified via the bgp confederation identifier router configuration command).

In a BGP speaker in autonomous system 6001, the bgp confederation peers router configuration 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 will 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 will be just like a normal eBGP update from a peer in autonomous system 60000.

router bgp 6001

bgp confederation identifier 60000 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. 170.70.70.1 is a normal iBGP peer and 199.99.99.2 is a normal eBGP peer from autonomous system 700.

router bgp 6002

bgp confederation identifier 60000 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 neighbor 199.99.99.2 remote-as 700

In a BGP speaker in autonomous system 6003, the peers from autonomous systems 6001 and 6002 are configured as special eBGP peers. 200.200.200.200 is a normal eBGP peer from autonomous system 701.

router bgp 6003

bgp confederation identifier 60000 bgp confederation peers 6001 6002 neighbor 171.69.232.57 remote-as 6001 neighbor 171.69.232.55 remote-as 6002 neighbor 200.200.200.200 remote-as 701

Cisco IOS IP Configuration Guide

IPC-344