Subject: [mobile-ip] Concerns about draft-mipv6-14 section 4.8

From: Thierry Ernst <[email-masked]>
Date: Mon, 30 Jul 2001 20:54:13 +0200

Dear all,

One of the changes of the MIPv6 draft from version 13 to 14 is the
addition of a section "Mobile Routers" (section 4.8) and a new
sub-option "Mobile Router Prefix Length" (section 5.5).  I have some
concerns about these additions that I would like to share with the WG:

o  I think that more issues are added than solved by this new
sub-option:
   - security (authorization)
   - How is it processed by the HA and the CNs
   - How is it used by the HA and the CNs
   - ...

o It does only solve part of the problems already highlighted last year
in the WG meetings and  in the mailing list

o There are a number of other problems that we have not even noticed or
at least debated.

o what is the exact meaning of "any home address" in section 5.5 ?

I think that the support of mobile routers and networks (let's call this
"Network Mobility Support") deserves more than a section.  Particularly
a terminology that defines what we are speaking about and that limits
the scope of the problem that could be solve by the MIP spec. would be
welcome prior to this.

Indeed, I am quite surprised to see a new section that has not
previously been discussed nor shared with the people on this mailing
list, particularly not with the authors of draft
http://www.ietf.org/internet-drafts/draft-ernst-mobileip-v6-network-02.txt.  
This draft that I wrote highlighted some issues in the MIPv6
specification for "Network Mobility Support".  As a result of past
discussions, some people have agreed that MIPv6 needs clarifications for
the HA to redirect packets to nodes behind the mobile router.  This is
not clarified in MIPv6-14, a clarification would have made more sense
than the addition of a new feature in the WG doc itself.   

Moreover, my draft has introduced a "Mobile Network Prefix" sub-option
that carries the prefix of the mobile network as part of the BU.  This
BU is sent to both the HA and CNs.  Following this proposition, security
concerns have been raised, particulalry about authorization. 
Authorization issues have largely accounted for the delay of the
acceptance of my idea.  The idea behind the sub-option introduced in
MIPv6-14 seems to be taken from my draft, though a bit more limited,
since it only carries the prefix length, not the prefix itself.   The
same authorization (and other security) concerns apply to this new
sub-option, particularly when it is sent to CNs.  I am quite amazed to
see that no one has waved the security flag this time.  Problably most
people are busy, or have missed this section.

Given the fact that "Network Mobility Support" is not yet a working
group item and that the problem is not even perceived by the WG, the
most immediate result relative to section 4.8 is that the MIPv6
specification may be further delayed.   This is something we can not
afford. MIPv6 has been delayed long enough, it's not the right moment to
introduce new feartures in the MIPv6 document itself.  The introduction
of new features would in turn introduce potential new holes (particulary
securiry holes) that would further delay the spec. for Proposed
Standard.

My conclusions are:

- Section 4.8 and sub-option "Mobile Router Prefix Length" SHOULD be
removed from the MIPv6 draft, 

- modifications to the MIPv6 draft specification MUST be discussed on
the mailing list prior to their addition in a WG document,

- extensions to the Mobile IPv6 specification, if not discussed on the
mailing list, MUST be presented in a separate document,

- Network Mobility Support SHOULD NOT be added in the MIPv6
specification itself - it is a distinct problem, it has its own solution
IMHO

- The problem and the requirements to solve "Network Mobility Support"
SHOULD be discussed first.  

BTW, I have written a new draft "Network Mobility Support in IPv6:
Problem Statement and Requirements"
http://www.ietf.org/internet-drafts/draft-ernst-mobileip-monetv6-00.txt
for the purpose of discussing the last item. If you have interest in
this discussion, a post on this mailing list PRIOR to the WG meeting
would be more than welcome.

Regards,
Thierry.

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From: "T.J. Kniveton" <[email-masked]>
Date: Mon, 30 Jul 2001 15:37:54 -0700

I agree with Thierry here - the discussions on the list and at meetings
have shown that there is interest in making mobile prefixes work within
the context of MIPv6 handovers. The key phrase here is problem scope --
it should be broken down to a solvable level, and especially limited
within the base draft (which I believe was the intention). To make it
really work, security issues must be solved first. Which leads us to the
question, for MIPv6 expediency's sake, why not leave it as a separate
draft?

-TJ

-- 
        T.J. Kniveton 
  Communications Systems Lab
     Nokia Research Center

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From: Michael Thomas <[email-masked]>
Date: Tue, 31 Jul 2001 07:52:34 -0700 (PDT)

I'll throw my support backing it out again
too. Mobile routers are going to involve a lot of
consideration, because they have some pretty far
reaching implications. They should be taken up as
a separate working group item instead of letting
it bog down mipv6.

       Mike