Subject: RE: [Mip6] I-D ACTION:draft-ietf-mip6-nemo-v4traversal-00.txt

From: "Soliman, Hesham" <[email-masked]>
Date: Tue, 25 Oct 2005 12:55:29 -0400

> > => Ah, well, the point of the draft is to introduce IPv4 
 > extensions 
 > > to MIPv6 so that it can support IPv4 CoAs/HoAs.
 > 
 > I do not agree with the MR obtaining a v4 CoA and then 
 > sending a BU with
 > a v4 Mobile Network Prefix.

=> Why?

 > 
 > It is natural for MR to obtain a v4 CoA and then send a MIP4 RegReq
 > containing a v4 Mobile Network Prefix (and not a v6 BU).  Would you
 > agree with this?

=> Please read the problem statement where it is clearly stated that
running MIPv4 and MIPv6 simultaneously in inefficient and prevent a node
from having mobility across different networks supporting different
IP versions.

 > 
 > > So I don't see why we should distinguish an HoA used by a 
 > host from 
 > > an HoA used by a router.
 > 
 > Normally I agree, but here we talk IP version numbers.

=> The whole point of this work is to make MIP work without
being tied to "version numbers"..

 > 
 > > The title of draft is clear that this is an effort for hosts and
 > > routers.
 > 
 > Well, ok with title as long as it does not try to give v4 
 > access to LFNs
 > with v6 MR connected to a v4 network.

=> Technical reasons please. It's really difficult to discuss issues
this way.

Hesham

 > 
 > The title is fine with me if it addresses giving v6 addresses to LFNs
 > (not v4 addresses) by a MIP6 MR connecting to a v4-only network.
 > 
 > Alex
 > 
 > 

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From: Alexandru Petrescu <[email-masked]>
Date: Tue, 25 Oct 2005 19:20:21 +0200

Hesham, for the discussion sake I strive to answer your technical questions.

Soliman, Hesham wrote:
>> I do not agree with the MR obtaining a v4 CoA and then sending a BU
>>  with a v4 Mobile Network Prefix.
> 
> => Why?

Because MIP4 could do it better.  Using MIP4 instead of MIP6 in this
particular scenario would avoid going through v6, so a level of
encapsulation eliminated.

Don't you think so?

>>  containing a v4 Mobile Network Prefix (and not a v6 BU).  Would 
>> you agree with this?
> 
>  running MIPv4 and MIPv6 simultaneously in inefficient

I've read it.  Two technical reasons raised my interest: (1) MIP6 is
better than MIP4 because has DHAAD and RO, (2) sending BU and RegReq
each time is not efficient.

For (1): DHAAD is not clear in terms of spec, and RO is not yet widely
deployed.

For (2): it's not necessary to send a BU and a RegReq simultaneously
when the MN changes only its v4 CoA and keeps its v6 CoA.  From a
particular implementation experience one may see that the v4 address
changes and the v6 address may be kept the same.

Are there other technical reasons in the draft?

> [running MIP4 and MIP6 simultaneously] prevent a node from having 
> mobility across different networks supporting different IP versions.

This can not be true, tell me.  Having both MIP4 and MIP6 in a same
node can not prevent mobility across different networks supporting
different IP versions.  On the contrary - it helps.  Because it would
use MIP4 when connecting to a v4 network and MIP6 when connecting to a
v6 network.

If the application needs to have a permanent v4/v6 Home Address even if
connected to the other IP version network then yes, one could use
enhancements.  But even in that case I have remarks I'd keep separate.

>>> So I don't see why we should distinguish an HoA used by a host 
>>> from an HoA used by a router.
>> 
> => The whole point of this work is to make MIP work without being 
> tied to "version numbers"..

That's a good goal.  But more precise would be to make MIP6 (not MIP)
beeing tied to "version numbers".

>> Well, ok with title as long as it does not try to give v4 access to
>>  LFNs with v6 MR connected to a v4 network.
> 

Technical reasons above.

Would you care to provide technical counter-reasons?

Alex