Routing asymetry and RPF check

Saku Ytti saku at ytti.fi
Wed Dec 11 17:03:46 UTC 2013


On (2013-12-11 16:10 +0000), R.P. Aditya wrote:

> Some problems never go away, just reappear periodically -- strict uRPF
> (and even loose uRPF) on transit provider peering interfaces are going
> to have unintended consequences as long as their is routing asymmetry

I can't imagine why uRPF/loose would be problematic. If you're originating
traffic from prefix which you're not advertising to DFZ and you still expect
it to work, your expectation are at fault, not uRPF/loose.

However uRPF/strict feasible won't work, while occasionally some people seem
to think it does.

-- 
  ++ytti



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