Dec 26 2008
BGP Route Aggregation
There are times when it is required to aggregate a set of prefixes. There are a number of reasons why you would want to do this such as, your peering transit edge may not accept certain size prefixes, you may want to reduce the size of the routing table in some part of your network etc etc.
Consider the topology below:-
Watch how to use the aggregate command below, or alternatively download the video and watch it on your iPod.
The commands used in the above setup are as below.
R1
interface FastEthernet1/0
description "Interface connected to R2"
ip address 10.0.0.1 255.255.255.252
!
router bgp 1
no synchronization
bgp log-neighbor-changes
neighbor 10.0.0.2 remote-as 2
no auto-summary
R2
interface FastEthernet1/0
description "Interface connected to R1"
ip address 10.0.0.2 255.255.255.252
!
interface Loopback0
ip address 192.168.0.1 255.255.255.0
!
interface Loopback1
ip address 192.168.1.1 255.255.255.0
!
interface Loopback2
ip address 192.168.2.1 255.255.255.0
!
interface Loopback3
ip address 192.168.3.1 255.255.255.0
!
router bgp 2
no synchronization
bgp log-neighbor-changes
network 192.168.0.0
network 192.168.1.0
network 192.168.2.0
network 192.168.3.0
aggregate-address 192.168.0.0 255.255.252.0 suppress-map SUPPRESS-2-ONLY
neighbor 10.0.0.1 remote-as 1
no auto-summary
!
access-list 1 permit 192.168.2.0 0.0.0.255
!
route-map SUPPRESS-2-ONLY permit 10
match ip address 1
