Subject: [Mip4] Changes for RFC3012bis - Issue 1

From: "Jayshree Bharatia" <[email-masked]>
Date: Tue, 30 Sep 2003 17:28:39 -0500

Hello all,

Based on the current discussion we have on this mailing list, I am planning
to make the following changes in RFC3012bis for Issue 1. Please let me know
if you have any issues with these changes:

Issue 1: Current draft (05 version) doesn't have description on how to treat
the router solicitations (mobility agent advertisement solicitations) in
terms of sending new challenge vs unused challenge. Due to this reason,
implementations differ significantly. This causes interoperability issues.

Proposal for Issue 1:

Change 1 (Accepted)
Section 2:
From:
The Challenge extension, illustrated in figure 1, is inserted in the Agent
Advertisements by the Foreign Agent, in order to communicate the latest
challenge value that can be used by the mobile node to compute an
authentication for its next registration request message.  The challenge is
selected by the foreign agent to provide local assurance that the mobile
node is not replaying any earlier registration request.  Eastlake, et al.
[5] provides more information on generating pseudo-random numbers suitable
for use as values for the challenge.

To:
The Challenge extension, illustrated in figure 1, is inserted in the Agent
Advertisements by the Foreign Agent, in order to communicate a previously
unused challenge value that can be used by the mobile node to compute an
authentication for its next registration request message.  The challenge is
selected by the foreign agent to provide local assurance that the mobile
node is not replaying any earlier registration request. Eastlake, et al. [5]
provides more information on generating pseudo-random numbers suitable for
use as values for the challenge.

Change 2 (New section - Accepted)
2.1 Handling of Solicited Agent Advertisements
When a foreign agent generates an Agent Advertisement in response to a
Router Solicitation [4], some additional considerations come into play.
According to the Mobile IP base specification [7], the resulting Agent
Advertisement may be either multicast or unicast. 

If the solicited Agent Advertisement is multicast, it MUST NOT generate a
new Challenge value and update its window of remembered advertised
Challenges. It must instead re-use the most recent of the CHALLENGE_WINDOW
Advertisement Challenge values.  

If the agent advertisement is unicast back to the soliciting mobile node
MUST be handled as follows: If the challenge most recently unicast to the
soliciting mobile node has not been previously used (as defined in Section
1.1), in SHOULD be repeated in the newly issued unicast agent advertisement,
otherwise a new challenge MUST be generated and remembered as the most
recent challenge issued to the mobile node. (For further discussion of this,
see Section 12.)

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From: Henrik Levkowetz <[email-masked]>
Date: Wed, 1 Oct 2003 01:23:07 +0200

Small nit:

> recent challenge issued to the mobile node. (For further discussion of this,

In the first line of the last paragraph, change "mobile node" to "mobile node, it"

Othewise, this looks fine to me.

	Henrik