set community question

[bma]

Hi

set community is in the route-map command with BGP, like:

route-map NET-BGP-Out permit 10

match ip address 99

set community 7020:20

What is mean for set community:7020:20?

What is for the number 7020:20?

Thanks

ben

[Richard Burts]

Ben

The BGP community is a value that you assign to routes. It is essentially a tag that is associated with the route so that someone else can evaluate the tag and make some processing decision based on the tag value.

In general the number before the colon in the community value (like 7020) would be your AS number. The number after the colon (like 20) is some arbitrary value that you pick.

So what this generally means is that you have agreed with some BGP neighbor that if they see routes from you with community (tag) value of 7020:20 that they should take some particular action about those routes.

HTH

Rick

[mohammedmahmoud]

Hi Ben,

Just to add a tiny detail on the prefect explaination by Rick, to add the community to the already existing communities you must use the "additive" keyword, in your example if the matched (in the ACL 99) routes has already got any communities it will be replaced with the "7020:20".

HTH,

Mohammed Mahmoud.

[bma]

Thanks all.

ben