Subject: [MOBILE-IP] hawaii drafts (june 99)

From: COELHO-ALVES Emmanuel CNET/DMR/ISS <[email-masked]>
Date: Wed, 11 Aug 1999 13:16:05 +0200

Hi,

I have some questions concerning hawaii drafts which have been submitted in
june 99.

Imagine we have split the access network into severals Domains. Each domain
has a Domain Root Router and each mobile host has a Home Domain.

The solution to manage mobility inside a Domain is clear.

I have some questions for clarification for the case where the mobile host
leaves its Home Domain and goes to a Foreign Domain 1.
During all the time the mobile host is in the Foreign Domain 1 we must have
a permanent forwarding from the Home Domain Root Router to the Foreign
Domain 1 Root Router.

Moreover imagine that the mobile host, after visiting the Foreign Domain 1,
goes to Foreign Domain 2.
What is the relation between Home Domain Root Router, Foreign Domain 1 Root
Router and Foreign Domain 2 Root Router when the mobile host does its
handover ? How to manage handover in this configuration ?
What is the solution to route incoming packets (I assume that routing
follows the classical IP model for outgoing packets) :
*       Home Domain Root Router -> Foreign Domain 1 Root Router -> Foreign
Domain 2 Root Router ?
or
*       Home Domain Root Router -> Foreign Domain 2 Root Router ? But if
this is the correct case, I don't see how to overpass the Foreign Domain 1
Root Router ?

In Hawaii solution, the Home Domain Root Router is a necessary point of
transit where all incoming packets must go before to join one of the Foreign
Domain Root Routers ?

Thanks in advance.
Emmanuel Coelho Alves

Emmanuel COELHO ALVES
Research Engineer
Third Generation Mobile Systems and Services
FRANCE TELECOM LABORATORY

Tel : +33 1 45 29 44 97
Fax : +33 1 45 29 43 99
Email : [email-masked]

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From: Ramachandran Ramjee <[email-masked]>
Date: Wed, 11 Aug 1999 14:40:34 +0000

Hello Emmanuel,

When a mobile host is handed off from foreign domain 1 to foreign domain
2, packets will flow directly from the home domain to foreign domain
2 (the reason is that the Mobile IP home agent at the home domain
will now directly tunnel packets to a (co-located) IP address assigned
from foreign domain 2 - thus, foreign domain 1 is bypassed
automatically).
So, your second scenario is correct.

In general , whenever a mobile host moves away from its home domain,
packets have to go through the Mobile IP home agent which is located
at the home domain root router in HAWAII. There are some optimizations
that can circumvent this - for example, 1) if the foreign domain is
in the same administrative control as the home domain and the
mobile host powers up in the foreign domain, then the
mobile host can be assigned a dynamic home address and home agent
in the foreign domain itself 2) for browsing-type client-based
applications
where maintaining an IP address continously is not critical, we
could allow the mobile host to give up its old home address and
obtain a new home address on domain crossings.

Hope this clarifies.

Cheers,
Ram