Re: [RRG] loc/id split and LISP

[jnc@mercury.lcs.mit.edu (Noel Chiappa)]

    > From: Dino Farinacci <dino@cisco.com>

    >>> How about the contentious issue of 240.0.0.0/4, should it be used as
    >>> the TLA for the EID namespace for IPv4?

    >> I think it actually makes more sense to use that space for LISP RLOC's.

    > Then all ISPs have to renumber if we do that. And they would have to
    > ask/force their customers to renumber their ETRs.

Actually, I wasn't suggesting that all RLOC's have to come from that space
(which certainly has the disadvantages that you list), merely that if it is
released, that it be used for RLOC's. 

I do not think we can require either namespace (EID's or RLOC's) to be
entirely allocated from 240/4; that would have the same problem for either
use, i.e. it would require a lot of renumbering.

Plus to which the IETF as a whole might not agree to allocate that space to
LISP, and one of the great charms of LISP is that it can start (and be
useful) with a very small initial deployment, without getting universal
buy-in.

    > Things won't be as clean as we would like but that is the cost of
    > incremental/least-cost changes to get a Loc/ID split deployed. 

Exactly.

    > I think its better to have 240.0.0.0/4 used for an EID namespace.

The problem with that is that if a host is given a 240/4 address as an EID,
for it to successfully operate, not only does *it* have to operate correctly
with 240/4 addresses, but so do *all the other hosts* with which it might
want to inter-operate. So, legacy hosts are going to make use of 240/0 for
EID's (or for host addresses in general) problematic.

Far better to use it in a more limited context, i.e. the LISP backbone.

And, like I said, once the rest of the namespace space becomes EIDs, we'll be
able to use the legacy space more densely, giving us extended life in that
part of the space.

	Noel

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