Subject: Re: [lisp] LISP basic questions

From: [email-masked] (Noel Chiappa)
Date: Mon, 18 Jul 2011 12:00:22 -0400 (EDT)

> From: Damian <[email-masked]>

    > Who exactly is supposed to run and configure ETRs and ITRs? In my
    > understanding it is those organizations, who participate in global
    > BGP routing, so basically those with their own ASes?

No; it is intended that any entity (no matter how small) which can benefit
from LISP's capabilities can/should run LISP. Those capabilities are many
and varied - 'separation of location and identity' is a very basic
architectural tool which will inevitably wind up being used in all sorts
of ways, including many we do not now see (in line with my favourite
aphorism about 'the sign of great architecture is not how well it does the
things it was designed to do, but how well it does things you never
imagined it would be used for'). So it might be anything as small as a
single user who wants to be multi-homed.

    > I suppose, it does not make sense for such smaller organizations to
    > set up their own ETRs/ITRs to serve the original purpose, as it
    > wouldn't offload the Internet's global BGP table.

The question of 'helping the routing' is a complicated one - one I don't
propose to examine in detail here. Although allowing for much smaller
routing tables (by advertising only RLOCs in the backbone, and not LEIDs)
was something that was discussed extensively early on (several years
back), after thinking about it for a while, it only becomes really
plausible at high deployment levels. (That is why the initial driver for
LISP deployment is likely to be other capabilities, e.g the traffic
engineering stuff.)

It's unclear at _initial_ deployment levels how much it will help the
routing in the DFZ. There may be _some_ help in the early stages - e.g.
DFZ entries intended to support traffic engineering, multi-homing etc can
be withdrawn once sites using them transit to LISP, provided there are
enough PITRs scattered around the network to make it feasible to depend on
LISP for those sites to communicate well with 'legacy' sites (which will,
in the initial stages, be the majority of the network).

    > Nevertheless, there are other benefits for smaller companies which
    > run multiple sites.

Those are definitely one class of users which can benefit immediately.

	Noel