If they set local pref for both peers and customers to 100 how do they ensure that the customer transit routes are announced to peers? The reason I ask this is because if a customer announces a customer of theirs to you that a peer also has as a customer you will have equal length routes for the same destination AS. While there are many ways to deterministicly prefer customer routes, local pref is the most common. Your core routers will only propagate the best route in their routing tables (normally). Assuming you have more than one BGP speaking router in your network, if you don't deterministicly prefer your customer routes (including their downstreams) then you won't deterministicly announce them for your customer. Most commonly when somebody pays for transit they want you to advertise their routes (including any customer routes they announce to you) to the world. Mike. On Fri, 14 Dec 2001, Me wrote:
All the responses I have gotten indicate that UUnet does indeed set local-pref on both customers and peers to 100 (or leave default in this case). Thanks for all the responses...
-- -sean Spoon!
On Fri, 14 Dec 2001, Christopher A. Woodfield wrote:
Date: Fri, 14 Dec 2001 12:01:39 -0500 From: Christopher A. Woodfield <rekoil@semihuman.com> To: German Martinez <gmartine@nic.gip.net> Cc: Me <smentzer@mentzer.org>, nanog@merit.edu Subject: Re: AS701 peer local-pref?
I think you misunderstood the question - what you have detailed here is a list of customer communities that UUNet accepts, what Sean is trying to find out is what internal localpref UUNet sets by default - do they automatically give prefixes from customers a higher localpref than prefixes heard from peers? I don't know for sure, but I'm thinking that they do, which makes sense - otherwise it's possible to send traffic to a peer when there could be a valid path for the traffic via a customer.
-Chris
On Wed, Dec 12, 2001 at 04:14:26PM -0500, German Martinez wrote:
SHORT NAME COMMUNITY WHAT IT DOES Local Pref = 80 701:80 set localpref 80 Local Pref = 120 701:120 set localpref 120 AS Path prepend 1 701:1 prepend 1x: 701 [cust-AS] AS Path prepend 2 701:2 prepend 2x: 701 701 [cust-AS] AS Path prepend 3 701:3 prepend 3x: 701 701 701 [cust-AS] Cust but not peers 701:20 propagate to custs, not peers keep cust routes in North America 701:30 send to custs & peers, but not 702, 703... keep AS7046 in AS701 no-export don't propagate beyond AS701 peers 701:666 don't propagate beyond this AS peers 701:1030 don't propagate beyond this AS
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On Wed, 12 Dec 2001, Me wrote:
Does anyone know what local-pref AS701 sets for their customers and their peers? I called their NOC, and was told that is was set to 100 for both, though I know most providers set local-pref on peers lower than customers. I just want to get confirmation on what i was told by their NOC.
TIA.
-- -sean Spoon!
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