BGP Routes Summarization

[TsepoLeribe]

Hi Network Gurus,

Can you kindly help, google did not help much, is there a way to summarize received BGP from the neighbor, aware of summarized routes that can be send, but can't find anyway i can summarized received routes. 

example

If i'm receiving a flood of prefix from AS2000 and want to summarize only on AS1000

B 192.100.100.0/24 [20/0] via 172.168.11.1, 00:00:15
B 192.168.11.0/24 [20/0] via 172.168.11.1, 00:00:15
B 192.168.12.0/24 [20/0] via 172.168.11.1, 00:00:15
B 192.168.13.0/24 [20/0] via 172.168.11.1, 00:00:15
B 192.168.14.0/24 [20/0] via 172.168.11.1, 00:00:15
B 192.168.15.0/24 [20/0] via 172.168.11.1, 00:00:15
B 192.168.16.0/24 [20/0] via 172.168.11.1, 00:00:15
B 192.168.17.0/24 [20/0] via 172.168.11.1, 00:00:15
B 192.168.18.0/24 [20/0] via 172.168.11.1, 00:00:15
B 192.168.19.0/24 [20/0] via 172.168.11.1, 00:00:15
B 192.168.20.0/24 [20/0] via 172.168.11.1, 00:00:15

Thanks in advance, appreciated.

[balaji.bandi]

Look at the example below and understand the concept :

https://www.ciscopress.com/articles/article.asp?p=2756480&seqNum=13#:~:text=The%20two%20techniques%20for%20BGP,the%20networks%20are%20not%20available.

here is an example for you to fix things :

router bgp 100
bgp log-neighbor-changes
network 172.16.0.0 mask 255.255.254.0
neighbor XXXX remote-as YYYYY
!
ip route 172.16.0.0 255.255.254.0 Null0

[Giuseppe Larosa]

Hello @TsepoLeribe ,

bgp aggregate-address                               summary-only can be used for this

you can aggregate routes that share a common part of the network portion in binary for example

192.168.16.0/24

192.168.17.0/24

192.168.18.0/24

192.168.19.0/24

can be aggregated in

192.168.16.0/22

router bgp 1000

aggregate-address 192.168.16.0 255.255.252.0 summary-only

be careful in creating summary routes that include component routes that do no exist.

Hope to help

Giuseppe