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.
Nick