Subject: hmip and mobile routers

From: Michael Thomas <[email-masked]>
Date: Wed, 28 Feb 2001 11:22:12 -0800 (PST)

Section 6 describes a mechanism of how mobile
routers might be supported by HMIP. However, I
think there is a fundamental category error being
made here. Namely, it is expected that behind the
mobile router are, in fact, mobile nodes. I see no
reason why this expectation should be made: there
is no reason why a non-mobile widget, say a PC,
should not be able to be attached to a mobile
router on a moving train. As currently defined,
mobile IP is only a requirement if the device
(router, host) is itself mobile. I do not see why
we should expand that requirement to anything
which is *behind* something that is mobile. In
fact there could be a huge downsides to doing so,
not to mention a whole lot of uncharted territory.

Consider a mobile router which services planet
Earth with fixed base stations to other planets
which it hand's off between at various points in
its rotation around Sol. Does that mean that each
and every handoff of Earth's mobile router will
require that each and every "mobile" device (read:
everything) re-register with a home agent? If not,
how would this work at all?

Also: what happens if there is more than one
router in between MR and the stationary host
in MR's subnet? What happens if there's more
than one MR? What delineates "my" MR versus
somebody else's MR?

It's possible I'm misreading that section, but if
I am it's probably because the section doesn't say
what needs to happen when the mobile router itself
moves. However, even if nothing catastrophic
happens, my original issue still stands:
non-mobile hosts shouldn't be forced to become
mobile aware by virtue of a mobile router some
arbitrary number hops away. 

		       Mike