Subject: [mobile-ip] Registration with co-located CoA via FA (question triggered by NAT traversal draft)

From: "Frode B. Nilsen" <[email-masked]>
Date: Thu, 23 May 2002 13:48:15 +0200

The latest NAT traversal draft (draft-ietf-mobileip-nat-traversal-02.txt)
includes a discussion on how to handle the case when the MN makes a registration
via a FA (eg. in response to a R-bit in an AA) using a co-located CoA (as
opposed to an advertised CoA from the FA).

Technicall this is possible, of course, but I had never though of the case
before and asked myself the following questions:

(1) Is this case within the scope of RFC3220?

(2) In what deployment scenarios would this case be natural and/or preferrable?

Taking a closer look at RFC3220 I find the following somewhat contradicting
statements:

[QUOTE BEGIN]
......
Section 2.1.1 Mobility Agent Advertisement Extension
-----------------------------------------------------
......
R  Registration required. Registration with this foreign agent (or another
foreign agent on this link) is required even when using a co-located care-of
address.
.......
Section 3.1 Registration Overview
---------------------------------
......
- If a mobile node is otherwise using a co-located care-of address, the mobile
node MUST register directly with its home agent.
[QUOTE END]

So, I am still a bit confused about (1) and would like other peoples view on the
interpretation here. This question should be pertinent for people making MIP
client sw but also for FA implementators.

Any comments on (2) would also be appreciated.

FrodeN

---

From: Bjorn Andersson <[email-masked]>
Date: Fri, 24 May 2002 10:33:12 +0300

> Section 2.1.1 Mobility Agent Advertisement Extension

However, the previous statement in section 3.1 says:

"-  If a mobile node is using a co-located care-of address,
    and receives an Agent Advertisement from a foreign agent on link on
    which it is using this care-of address, the node SHOULD register
    via that foreign agent (or via another agent on this link) if the
    'R' bit is set in the ed Agent Advertisement message."

The sentence you quoted says "otherwise", i.e. if there is no foreign
agent advertisnig the 'R' bit. I don't see any contradiction.

  Bjorn

-- 
Bjorn Andersson <[email-masked]>                       +358 50 341 2556
Lifix Systems Oy <http://www.lifix.fi/>                 PGP id 5AFC144B
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