Subject: [nemo] IPv6 prefix delegation

From: "Pekka Pääkkönen" <[email-masked]>
Date: Mon, 4 Nov 2002 10:12:49 +0200

Alex, thanks for the comments. Many things got sorted out.

-----Original Message-----
From: Alexandru Petrescu <[email-masked]>
To: Pekka Pääkkönen <[email-masked]>
Cc: [email-masked] <[email-masked]>
Date: 2. marraskuuta 2002 15:55
Subject: Re: [nemo] IPv6 prefix delegation

>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.
>

So it is assumed that TLMR1 and TLMR2 have the same HA from which they get a
MNP?
I was considering a case when these TLMRs would have different HAs and a
different MNP at each HA
to be delegated for mobile networks. In that case there might be problems
(also with the security issues)
in delegating a MNP to the mobile 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?
>
>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
>
>

---

From: [email-masked]
Date: Mon, 04 Nov 2002 16:55:58 +0100 (CET)

> So it is assumed that TLMR1 and TLMR2 have the same HA from which they get a

Yes, I guess so.  This would not prevent to have 3 MNPs and 2 MRs though,
but still the same HA.

> in delegating a MNP to the mobile network?

Aha... I see.  This reminds me about requirements, again.  Let
me explain why.

In the Yokohama monet minutes, there's a warning
inviting to take care when one multi-homed PAN-mobile
network visits a car-mobile network and visits a ferry-mobile
network, not to give access to all users in the boat through
that person's multihomed mobile router.

Put differently, maybe we can imagine a requirement, where it
is stated that a zombie MR (w/o its mobile link) can not wander around,
find a mobile link that already has a TLMR, and then offer its services
to the mobile link such as the mobile link accepts a new TLMR that has
a different HA than the original TLMR.

Maybe we can find a phrase to express that this scenario is
not in the goals.

In all cases, the multi-homing requirements should describe what
are the goals of multi-homing and what are not its goals.

Alex