North American Network Operators Group

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Re: URPF on small BGP-enabled customers?

  • From: Pete Templin
  • Date: Fri Jun 03 10:14:31 2005

[email protected] 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.