Thanks a lot! tested bgp_local_pref and works fine! prepending with the peer AS didn't cross my mind. Thanks. Arjan Filius On Thu, 2010-06-10 at 14:13 +0200, Ondrej Zajicek wrote:
On Thu, Jun 10, 2010 at 09:57:59AM +0200, Arjan Filius wrote:
Hello bird-users,
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running bird 1.2.3 ppa x64 ubuntu 10.04LTS. 2 bird routers connected with 2 iBGP sessions over different links.
I'm trying to route specific outgoing traffic over a specific Transit. It starts with that I'm not really sure how to do it, so tested a bit. Setting Local performance on protocol definition works just fine for a complete Transit, however when i want to do it more fine grained, i run into trouble.
You mean local preference (LOCAL_PREF BGP attribute)? You can set local preference in filters for specific routes like other attributes (using 'bgp_local_pref'). That would probably do what you want.
First started with prepending routes in bgp input filter with my own AS, which works OK on a single bird router, however, with iBGP all prepended local AS-es are stripped, and that concept doesn't work.
You can also prepend peer AS on incoming routes. If you keep such routes in your AS it should be OK.
Then, started to set the preference in the bgp input filter, which also works fine on a single bird router, but that preference seems not to propagate to the second iBGP router.
Yes, (protocol) preference is not BGP attribute, but it is internal BIRD metric to be able to compare routes from different protocols (BGP/OSPF/static ...)
Protocol preference (route attribute 'preference') and BGP local preference (route attribute 'bgp_local_pref') are different concepts.