Subject: Re: [MOBILE-IP] WG Last Call: Mobile IP v6:draft-ietf-mobileip-ipv6-13.txt

From: Francis Dupont <[email-masked]>
Date: Sun, 3 Dec 2000 22:24:27 +0100

The section 10.20 Returning Home is still wrong about neighbor discovery
issue, it states that:

   If the mobile node
   does Neighbor Solicitation to learn the home agent's link-layer
   address, in this special case of the mobile node returning home, the
   mobile node MUST unicast the packet, and in addition set the Source
   Address of this Neighbor Solicitation to the unspecified address
   (0:0:0:0:0:0:0:0).  Since the solicitation is unicast, the home agent
   will be able to distinguish from a similar packet that would only be
   used for DAD.

 The previous I-D doesn't mandate unicast (the change seems to be an answer
to my concern with I-D 12) but this cannot work because the mobile node
needs the home agent's link-layer in order to unicast a neighbor
solicitation to the home agent...
 The mobile node MUST multicast the neighbor solicitation to the
solicited-node multicast address of the home agent (this doesn't need
to be in the next draft but changes should explain why multicast doesn't
work).
 The problem is with the source address, if no address of the mobile node
can be used then the mobile node MAY use the unspecified address (::)...
(we should keep a MAY because even if the home agent should take it as a DAD
for its own address it works, but it must be used only when there is no
obvious solution, as using the link-local address when it is not
registered/protected).

Regards

[email-masked]