Re: [Idr] Last Call: <draft-ietf-idr-ix-bgp-route-server-10.txt> (Internet Exchange BGP Route Server) to Proposed Standard

Nick Hilliard <> Wed, 01 June 2016 11:17 UTC

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Date: Wed, 01 Jun 2016 12:17:00 +0100
From: Nick Hilliard <>
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To: Marco Marzetti <>
Subject: Re: [Idr] Last Call: <draft-ietf-idr-ix-bgp-route-server-10.txt> (Internet Exchange BGP Route Server) to Proposed Standard
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Marco Marzetti wrote:
> I agree with you that you can run a route server and insert your ASn in
> the path, but i think that is a lack of common sense which brings only
> contraries and no benefits.
> About RFC2119: It says that "SHOULD NOT" implies a valid reason to
> accept a behavior, but i can't find any.

I agree that it is not a clever thing to do. The valid reason to accept
the behaviour is that it works in practice: some IXPs have done this in
production, in many cases for years.

There is a secondary reason: some rs client bgp stacks don't support the
option to accept an AS path from the RS where the leftmost entry on the
AS path != peeras.

These are not "good" reasons in the sense that they mandate behaviour
which is suboptimal, but they are valid reasons.