BGP Summarization
BGP can summarize routes advertised to peers using the aggregate-address command. As an example, assume you have multiple subnets of the 172.30.0.0/16 network and you want to advertise this summary if any of these subnets exist:
router bgp 1 neighbor 10.1.1.1 remote-as 2 network 172.30.1.0 mask 255.255.255.0 network 172.30.8.0 mask 255.255.255.0 network 172.30.14.0 mask 255.255.255.0 network 172.30.25.0 mask 255.255.255.0 network 172.30.42.0 mask 255.255.255.0 aggregate-address 172.30.0.0 255.255.0.0
The preceding configuration will advertise the 172.30.0.0/16 prefix and all of the subnets for which there are network statements and matching routes in the routing table. To advertise the summary address only, you can use the ...
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