Subject: [MOBILE-IP] A Question on Mobile IP Regional Tunneling

From: Karann Chew <[email-masked]>
Date: Fri, 28 Jul 2000 16:40:48 +0100

Hi folks!

I've just read "draft-ietf-mobileip-regtun-03.txt".
A question strike me...

Section B1. Registration with Home Agent says:

"If there is a hierarchy of foreign agents between the GFA and the
announcing foreign agent, the foreign agent MAY include the corresponding
addresses in order between its own address (first) and the GFA address
(last):
    -  Address of announcing foreign agent
    -  Address of the next higher-level Regional Foreign Agent (RFA)
    -  ...
    -  Address of GFA"

In other words, the leave FA advertise the addresses of RFA and GFA
located along the path towards the root.  But what's the need of
advertising all these addresses?  Why not advertising only the
serving-FA's and GFA's addresses only, with 'I' bit set?

Apology if this question has been addressed.  I missed the past
discussions, and am currently trying to catch up with the works
related to micro mobility management done in this group.

Cheers!
        Karann

******************************************
Karann Chew
Mobile Communications Research Group
Centre for Communication Systems Research
University of Surrey, UK
******************************************

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From: "Charles E. Perkins" <[email-masked]>
Date: Fri, 28 Jul 2000 09:04:58 -0700

Hello Karann,

First, since I'm typing away, let me again register my objection
to the term "micromobility":
- It gets confused with "link mobility"
- The area over which mobility may be managed might be not
  at all "micro"
So, the term is _harmful_ in my opinion.  "Intra-domain" mobility
is much, much better.

Having said that, here is my answer to your question.

It turns out to be easier for the mobile node to determine
the crossover router, if the information is available.
However, if the router hierarchy does not wish to advertise
its internal structure, then it should _still_ be possible
for the system to work.  Thus, in the draft, we allowed for
both possibilities.  If no one implements the fully advertised
model, then it will be deleted from the draft.

Regards,
Charlie P.