Thus spake Tony Li
I don't see how we'd get incremental deployability with truly split
address spaces.
One way would be to split them in such a way that they jointly remained
syntactically similar to the original address space. This
is one of the cuter things about GSE. Then new generation
systems could recognize them as split (via a compatibility bit
someplace) and to legacy systems, it would appear to be a
legacy address.
I suppose that's a "split"; I thought Russ was worried that there would be
two (potentially overlapping) address spaces, one for providers and one for
customers, as opposed to a single address space which was divided into RLOCs
and EIDs. For instance, there's been mention of using IPv6 for EIDs and
IPv4 for RLOCs, which has some interesting properties.
Along your lines of a split, I like the idea of using 4000::/3 for
LISP-mapped EIDs and deprecating PI space in 2000::/3. It's a bit tougher
to apply the same split to v4 since there won't be any /8s left by the time
a solution is standardized...
If we are able to constrain BGP tables to only transit ASes, the DFZ
becomes a lot smaller and we can afford to let everyone,
even home users, multihome with PI space. (Of course, there's
a hidden assumption there that the number of transit ASes will
remain under control, but I haven't seen anyone dispute that.)
There's also a hidden assumption there that you can do that. One
practical definition of PI space today is that your prefix is in BGP.
That's one way of looking at it, but that's only a result of the fact that
PI space _can't_ be reached today unless a prefix is in BGP. Technically,
if I got a block from my RIR for internal use, it's still PI space even if
it never shows up in BGP.
With LISP, I envision a world where PI space and EID blocks are the same
thing, and neither shows up in the DFZ -- other than a single EID aggregate
that leads to anycast ITRs (to handle legacy senders).
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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