Subject: (IPng 7191) proxy neighbor advertisement for mobile IPv6 *node*

From: Francis Dupont <[email-masked]>
Date: Wed, 17 Feb 1999 23:59:02 +0100

There are three sections about proxy neighbor advertisement:
 - "9.5 Intercepting ..." (draft-ietf-mobileip-ipv6-07.txt)
 - 10.17 "Returning Home" (the same document)
 - "7.2.8 Proxy Neighbor Advertisements" (RFC 2461 "Neighbor Discovery")
There are many details about the S (Solicited) flag and the O (Override)
flag (which exists mainly for proxy/anycasts) but nothing about the
value of the third R (Router) flag!

I can see only three possibilities:
 - always put zero (0), why?
 - always put one (1), for instance because the sender of the packet is
   a router but the Router flag is relative to the target not to the source
   (sender is an ambiguous term but the processing of Neighbor Advertisement
   in "7.2.5 Receipt of Neighbor Advertisements" (RFC 2461) is accurate)
 - put one if and only if the target is a router.
Obviously the third is the correct one but there is two cases
where the target and the source are not the same:
 - anycast but nodes with anycast addresses MUST be routers then
   in this case the problem is solved (set the Router flag)
 - proxy, especially when the target is a mobile node which has moved off-link
In the second case there is *no* way to know if the node is a host or a router.

I can propose two solutions:
 - restrict mobile IPv6 to hosts, we don't really know how to manage
   mobile routers with IPv6 but I believe this is a bit drastic
 - add a new flag in home registration

Regards

[email-masked]

PS: I am not on the mobile IP mailing list then this mail can be reject
by anti-spam stuff and of course I'll get no answer to the list
(I expect to find the discussion on ipngwg list).
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