Community issue

[044102947]

Hi all

I have 2 links to differnet ISP's, we have implemented a blackhole routing.I can advertise routes tagged with communities specified by my upsteam providers, but the problem is when i advertise a route with community speicifed by ISP-1 it is advertised to ISP-2 too.What is yor suggestions how can i prevent advertisment of routes tagged by community assigned by isp-1 to appear on ISP-2.

Thx.

[pkhatri]

At what point are you attaching communties to your routes ? Is it when you redistribute the routes into BGP ? It might be better to use an outbound route-map on each of your BGP sessions and then apply the community there.

Hope that helps - pls rate the post if it does.

Paresh

[044102947]

The way I am doing this is :

route-map DDOS permit 10

set community 60:10

router bgp xxx

network xx.xx.xx.xx mask 255.255.255.255 route-map DDOS

[Harold Ritter]

you should add a match ip address statement in the route-map for the specific prefix and apply it outbound using the neighbot statement.

router bgp xxx

neighbor ISP1 route-map DDOS out

neighbor ISP1 send-community

route-map DDOS permit 10

match ip address 1

set community 60:10

access-list 1 permit xx.xx.xx.xx

Hope this helps,

[Harold Ritter · Accepted solution]

You are probably configuring the route-map on the network statement, right? You should apply the route-map outbound on the specific ISP as follow:

router bgp xxx

neighbor ISP1 route-map ISP1 out

Hope this helps,