AS-PATH prepends

[sburgin]

do AS-PATH prepends affect *all* routes advertised or can prepends be applied on a per route basis using BGP v4 ?

[Harold Ritter]

You can apply the as-path prepend to a subset of the routes you advertise.

Use the match statement inside the route-map to determine which routes are going to be affected or not based on the prefix it self or other values such as community or the as-path.

Hope this helps,

[sburgin]

so, you're saying to use a route-map which includes a 'match ip address prefix-list 'foo'

'set as-path prepend AS# AS# AS# .....'

-and then on another line -

'ip prefix-list foo seq 5 permit 172.16.100.0/24'

-and this will prepend only the 172.16.100.0/24 route with those prepends even though we want to advertise all of 172.16.0.0/16 with no additional prepends ?

[Harold Ritter]

Correct.