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Re: [RRG] Comments on draft-lewis-lisp-interworking



Thus spake "Dino Farinacci" <dino@cisco.com>
It's unfortunate that it wouldn't change, because the provider would need to know about both the PA allocation and the EID assignment.
Effectively, it's double the hassle factor.

The provider doesn't have to know about EID-prefixes. It can filter and uRPF on the locator address that is part of it's own block.

Packets coming out of a LISP site will have a source address in the EID
prefix if they're headed to a non-LISP site or depending on a PTR or
ISP-provided ITR to reach other LISP sites; all of those cases give you uRPF
or filtering problems.  Packets will only have a source address in the RLOC
prefix if they've been encapsulated by a customer ITR for transmission to
another LISP site -- and we must assume that will be rare, at least
initially.

Tony is correct; the ISP now has to maintain routes (for uRPF) or filters
for two prefixes per customer instead of one.  OTOH, that is a cost paid in
one place, while the benefit of LISP accrues to every BGP router with a full
table.  That seems like a reasonable trade-off...

S

Stephen Sprunk         "God does not play dice."  --Albert Einstein
CCIE #3723         "God is an inveterate gambler, and He throws the
K5SSS        dice at every possible opportunity." --Stephen Hawking


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