On 2010-02-11, Ivo Chutkin <[email protected]> wrote: >>> match to $my_upstream_1 source-as {some_as} set prepend-self 4 >>> >>> I would like to prepend my as to make as path longer for "some_as" >>> trough my_upstream_1 and make it to prefer path trough my_upstream_2. >>> It does not produce error with bgpd-n but there is no effect as well. >> >> Are you certain it has no effect (and how?) - you can't rely on >> AS path prepending to change how traffic flows, if someone gives you >> a higher localpref they'll use that path irrespective of the path length. >> >> > Hi Stuart, > I am "certain" as I don't see my prepend on some_as looking glass. > > The actual filter looks like this without the comment: > > match to $spnet_bg #(AS8717) sourse_as 9070 set prepend-seff 4 > > and this is what I see on 9070 looking glass:
This filter affects prefixes you send to the peer, and only those with source_as 9070. Unless you are providing transit for 9070 you won't be sending anything to 34224 that matches this (and if you are, it wouldn't be a useful thing to do, as 9070 won't accept routes with their own AS in the path). If I understand correctly, you'd like 9070 to see a longer path to you via 34224, but not affect things for other AS that see you via 34224. I think there are just two ways you can do this via prepending 1. ask 34224 to prepend their announcements to 9070. Some providers let you set communities on your prefixes to do this, see e.g. whois -r as3356|more +/ties.acc but many do not. 2. ask 9070 to prepend the paths they receive from 34224.
