Subject: [nemo] IPv6 prefix delegation

From: "Pekka Pääkkönen" <[email-masked]>
Date: Fri, 1 Nov 2002 13:46:17 +0200

-----Original Message-----
From: Alexandru Petrescu <[email-masked]>
To: Pekka Pääkkönen <[email-masked]>
Cc: [email-masked] <[email-masked]>
Date: 29. lokakuuta 2002 19:04
Subject: Re: [nemo] IPv6 prefix delegation

>"Pekka Pääkkönen" <[email-masked]> writes:
>>                    CN
>>                     |
>>                ---------------
>>              (  Internet    )--HA
>>                ---------------
>>                    |
>>                   AR                           linkX/prefix X
>>                    |                        MR2-------------------MN2
>>                    | link1/prefix1
>>                    |
>>                   MR1
>>                    |
>>                    | link2/prefix 2
>>                    |
>>                   MN1
>
>Good picture.
>
>> Hi all.
>> Please consider the above picture. MR2 and MN2 on linkX want to
>> establish a NEMO-network (consists of MR2 and MN2).  It is assumed
>> that MR2 needs to dynamically get a IPv6 prefix X for the NEMO,
>> because the NEMO-network is created in an ad-hoc way.
>
>That's a nice statement, but if it is done in an ad-hoc way, then I
>believe it's a manet problem, not a NEMO problem.  I think we can see
>it as a NEMO problem only if we want MN2 to get a new CoA once MR2 had
>attached under MR1, but I thought this will not happen and MN2 will
>not have to deal with any form of mobility (I assume that's why you
>attached MN2 to MR2, presumably like an LFN).
>
>> When this new NEMO is created and attached to Internet via AR or MR1
>> the following questions arise:
>>
>> 1.) Where will the IPv6 prefix for the NEMO be received from? From
>> AR, HA or MR1 or some other network entity?
>
>So it's assumed that a mobile network will receive a new prefix
>(instead of a CoA), let's say a CoP (Care-of Prefix) when it moves.
>This might be very useful for RO.  This might be done with Router
>Renumbering as well.  This might be done with other routing protocols
>as well.
>
>> 2.) What are the protocol requirements for IPv6 prefix delegation in
>> a NEMO environment?
>
>Off the top of my head: security requirements.
>
>> 3.) Do we need IPv6 prefix delegation for NEMO environment? The
>> picture suggests yes, because no IPv6 prefix has been initially
>> allocated for the NEMO.
>
>Initially, there's a prefix allocated to the mobile network when the
>mobile network is at home.  Let's call it MNP (mobile network prefix).
>The mobile network can continue to use this MNP wherever it moves, and
>only the MR will obtain a CoA (not a CoP).  The MR maintains a
>bidirectional tunnel with the HA through which all communication of
>LFNs goes.  This has obvious inconvenients like multiple tunnels when
>nested nets (for which RRH is a solution), or lack of RO with the CN
>and so on.  These drawbacks should be described somewhere.  But
>inspite of these obvious drawbacks it still offers a solution for
>mobile networks, nested nets, with minimal modifications to Mobile
>IPv6.  Looks like a good first step.
>

OK. So a MNP will initially be assigned to the NEMO-network and the MR just
has to know that
a certain MNP has been assigned to the NEMO-network to which the MR is
attached to?
Consider that we have a NEMO-network which has multiple MRs on the top level
(TLMRs).  Each MR has to know
the MNP which has been assigned to the NEMO-network. Aren't there real
problems related to this use case since
each TLMR has to be informed somehow the MNP which has been assigned to the
NEMO-network? Or does
NEMO-WG not consider the initial formation of the NEMO-network and just
assumes that
a MNP will somehow be assigned to a NEMO-network?
Or am I missing something?

Pekka

>> Should these issues be concerned with in the requirements related to
>> NEMO?
>
>I think yes, in the NEMO RO requirements case.
>
>Alex
>
>

---

From: Alexandru Petrescu<[email-masked]>
Date: 01 Nov 2002 21:39:28 +0100

Pekka, here are my thoughts.  The issues may indeed look tangled, but
maybe there's a simple way out of this if we consider them from a
Mobile IP standpoint.

"Pekka Pääkkönen" <[email-masked]> writes:
> OK. So a MNP will initially be assigned to the NEMO-network and the
> MR just has to know that a certain MNP has been assigned to the
> NEMO-network to which the MR is attached to?

Yes, exactly.  The nice thing about MNP is that we can also call it
Home Prefix (or HP).  That is very stable and never changes.  The MNP
on the mobile network will move anywhere around the Internet, and the
HA will redirect traffic to its current position (the CoA of the MR).

Contrast this to the ephemerality of the prefix obtained via prefix
delegation.  If I understand correctly what was said until now, it is
that a mobile link will arrive in a visited domain and will obtain a
prefix valid in that visited network.  So the mobile link can stay
there as long as it wants and be linked to the Internet.  Once it
moves away, the mobile link must get rid of that delegated prefix,
since it is valid only in the respective visited network.

> Consider that we have a NEMO-network which has multiple MRs on the
> top level (TLMRs).

You've just enunciated the multi-homing aspect.  The NEMO-network can
be multi-homed, either with two interfaces on the MR, or with several
TLMRs, as the definition goes.  I do not know how this works exactly,
but it should work somehow.

> Each MR has to know the MNP which has been assigned to the
> NEMO-network. Aren't there real problems related to this use case
> since each TLMR has to be informed somehow the MNP which has been
> assigned to the NEMO-network?

The way that TLMR1 knows about MNP, is the same way that TLMR2 knows
about MNP.

> Or does NEMO-WG not consider the initial formation of the
> NEMO-network and just assumes that a MNP will somehow be assigned to
> a NEMO-network?

I think that the NEMO-network (new term Thierry!) is not formed
dynamically by an MR joining a link of LFNs.  Both MR and LFNs have
the same home, from the start.

I think that many people see the MR permanently attached to the mobile
link, thus the MNP is pre-configured on the MR.  Something like taking
a "slice" of a fixed home network and moving it away.

In Mobile IPv6, there's the concept of Home Agent discovery, where an
MH discovers its HA and then auto-configures a Home Address for
itself.

NEMO goes from MH to MR, so this could be extended to an MR like this:
MR first does what MH does (discovers HA and auto-configures a Home
Address); and configures a bidir MRHA tunnel to its HA; and then
obtains from its HA an MNP (mobile network prefix, or the home prefix)
for its mobile link.  Maybe _this_ could be done with Prefix
Delegation.  The goal of this mechanism would be to not have the MNP
preconfigured on the MR, but obtained dynamically from its HA.  This
MNP would continue to stay stable every time MR changes its CoA.

This is different from MR using Prefix Delegation to obtain a new
prefix (CoP) each time it moves.

Or maybe this is what you wanted to say.

My humble oppinion,

Alex