Thus spake "Dino Farinacci" <[EMAIL PROTECTED]>
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
Well that depends:
1) If the source address is indeed an EID, and you want your packets
to return from a non-LISP site, then they are routable and hence can
be filtered or uRPF'ed against.
2) If the source address is out of EID space, but the ITR is doing
LISP-NAT, then again you have a routable address you can filter and
uRPF against.
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.
Or translated into an RLOC.
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...
No, I disagree. It has to keep a single set of filters, and that is
based on the source address leaving the site. That can be the 1)
source host's address, 2) the ITR's RLOC addres, or 3) a translated
address. In all cases, they are out of the attached provider block.
There is no choice here, we have to do this. And if we don't accept
it, nothing will come close to getting deployed. So we have to try to
make it work as simplest as we can.
Dino
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