[81286] in North American Network Operators' Group
Re: URPF on small BGP-enabled customers?
daemon@ATHENA.MIT.EDU (Pete Templin)
Fri Jun 3 10:13:55 2005
Date: Fri, 03 Jun 2005 09:13:26 -0500
From: Pete Templin <petelists@templin.org>
To: will@loopfree.net
Cc: nanog@merit.edu
In-Reply-To: <20050603102530.GA23951@loopfree.net>
Errors-To: owner-nanog@merit.edu
will@loopfree.net wrote:
> This is new to me, but I haven't bought any new transit in the past 18 months -- is
> this common practice on multihomed BGP customers now? I could force things to work
> by always advertising all my prefixes out to them with the obvious downside of
> living in fear of my outbound traffic being dropped if I ever need to withdraw any
> of them.
I (a network much, much smaller than Sprint) do uRPF on all ports, but
also inform BGP customers (nine-page handoff documentation) that they
are uRPFed. However, in conjunction with community support for
adjusting localpref, we set a sufficient weight on the announcement so
that the edge node sees the customer link as preferred even if the rest
of our network doesn't, and therefore the uRPF check passes.
I don't think advertising more-specifics through other connections would
actually work, as the Sprint edge router would still want to reach the
more-specifics through the Sprint network, rather than the customer
link. It's all a matter of what the FIB says.
pt
