BGP not to advertise a prefix

[Alex Vector]

Hey!

I need to tell my eBGP-neighbor not to advertise a prefix to its specific neighbor. I know that BGP community no export tells BGP neighbors to advertise a prefix only to iBGP neighbors.

Thus with no-export I can tell my neighbor not to send a prefix to its all eBGP neighbors, but I want it NOT to send a prefix to its SPECIFIC eBGP-neighbor and to advertise the prefix to all other eBGP neighbors. Is it possible to do with BGP communities?

[Giuseppe Larosa · Accepted solution]

Hello @Alex Vector ,

it is possible to do what you want to achieve using BGP communities but you and the people managing your direct eBGP peer must agree  a) on using BGP communities

neighbor x.x.x.x send-community

b) and you and the other people must agree on the meaning to give to a specific BGP community value so that they can implement the desired policy. All prefixes with that specific BGP community value will be filtered out toward the remote eBGP neighbor.

Note: if the remote eBGP neighbor is a customer of your directly connected eBGP peer it might be difficult to have them filter the prefix toward a customer that pay for receiving a BGP full table.

Hope to help

Giuseppe

[Alex Vector]

Thank you so much for your reply!
Can you tell me, please, are there any other tools that I can use to achieve what I want?

[Giuseppe Larosa]

Hello @Alex Vector ,

actually no there no other tools to be used for this scenario in BGP, BGP communities are a way to tag BGP prefixes, and notice that without the collaboration of the people managing your direct eBGP peer you cannot achieve the desired result.

Hope to help

Giuseppe

[Alex Vector]

Thank you!