Subject: [Mip6] RE: When behind NAT MN should have a real IPv6 CoA not mapped (was: Again on port number for DS-MIPv6)

From: "Soliman, Hesham" <[email-masked]>
Date: Fri, 28 Apr 2006 12:54:31 -0700

I just want to make one point as clear as I can:

 >
 > And finally, what do you guys have against MN having a real IPv6 CoA
 > when behind NAT?  What would that break?  

=> The fact that it is behind a NAT should make it very clear that the
visited network does not support IPv6. Therefore, getting an IPv6 CoA
(which is, 
by definition, provided by the visited network), is not possible.
Therefore, 
the draft doesn't talk about getting an IPv6 CoA when the MN is in an
IPv4
network.

   Wouldn't software 
 > reusability
 > be good?  3775, 3776 and bootstrapping work work unmodified.

=> What does bootstrapping and 3775/6 have to do with stateless
autoconfig
(defined in 2462)? Nothing...

Hesham

 > Alex

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---

From: Alexandru Petrescu <[email-masked]>
Date: Fri, 28 Apr 2006 22:27:13 +0200

> I just want to make one point as clear as I can:

Sure!

>> And finally, what do you guys have against MN having a real IPv6 
>> CoA when behind NAT?  What would that break?
> 
> => The fact that it is behind a NAT should make it very clear that 
> the visited network does not support IPv6.

Indeed, it doesn't.

> Therefore, getting an IPv6 CoA (which is, by definition, provided by
>  the visited network)

Definition sounds logical.

But if while in the visited network the MN opens a tunnel interface,
would this tunnel be able to have an IPv6 address?  I guess yes.  Do you
mind me calling it a "CoA"?  Can I call it a "NAT IPv6 CoA"?

Otherwise, if the "visited network" is actually the tunnel link, can I
still say that the IPv6 CoA of the MN when the tunnel link is up is a CoA?

Otherwise, "visited network" isn't in 3753 "mobility related
terminology", and neither in the Definitions of 3775, although used
there extensively.

But let's not blindly abide some definitions here.  Technically speaking
what wrong do you see with a NAT IPv6 CoA?  What would it break?  What
software re-use would make it impossible?

> Therefore, the draft doesn't talk about getting an IPv6 CoA when the 
> MN is in an IPv4 network.

Oh, I see.  Maybe it should, because otherwise the DS-MIPv6 draft should
talk about decrementing some TTL when encapsulating.  It currently doesn't.

>> Wouldn't software reusability be good?  3775, 3776 and 
>> bootstrapping work work unmodified.
> 
> autoconfig (defined in 2462)? Nothing...

Well, from implementation again, if the first thing one does is to have
stateless auto-config (i.e. have a real IPv6 CoA) running on the UDP
tunnel, then bootstrapping would work unmodified, 3776 too.  Otherwise I
wonder how 3776 would work with IPv4 Care-of Addresses, especially when
there is no real IPv6 Care-of Address, especially when the IPv4 CoA
behind NAT, so an IPv4 address is common to two nodes.

Alex

---

From: Henrik Levkowetz <[email-masked]>
Date: Sat, 29 Apr 2006 00:51:34 +0200

Hi,

With great hesitation, I'm afraid that I'll have to state my belief
that you're now Trolling, Alexandru ...

on 2006-04-28 22:27 Alexandru Petrescu said the following:
...

---

From: Alexandru Petrescu <[email-masked]>
Date: Sat, 29 Apr 2006 01:03:51 +0200

> that you're now Trolling, Alexandru ...

Sorry, none of my intentions to troll.

I can state with sufficient confidence that when MN behind NAT it gets
an IPv4 private address, and uses the NAT's public IPv4 address to open
UDP tunnels to the HA (that I call a GW).  With this setup, the MN can
arrange itself a publicly routable IPv6 address, configured right on its
UDP tunnel interface.  You're calling me trolling because I call that a
"IPv6 CoA on MN behind NAT".  I hope not.

With all due respect, I refrain on this topic of calling it so.

Alex

> 
> on 2006-04-28 22:27 Alexandru Petrescu said the following: ...
>> But if while in the visited network the MN opens a tunnel
>> interface, would this tunnel be able to have an IPv6 address?  I
>> guess yes.  Do you mind me calling it a "CoA"?  Can I call it a
>> "NAT IPv6 CoA"?
>> 
>> Otherwise, if the "visited network" is actually the tunnel link,
>> can I still say that the IPv6 CoA of the MN when the tunnel link is
>> up is a CoA?
>> 
>> But let's not blindly abide some definitions here.  Technically
>> speaking what wrong do you see with a NAT IPv6 CoA?  What would it
>> break?  What software re-use would make it impossible?
>> 
>>> Therefore, the draft doesn't talk about getting an IPv6 CoA when
>>> the MN is in an IPv4 network.
>> Oh, I see.  Maybe it should, because otherwise the DS-MIPv6 draft
>> should talk about decrementing some TTL when encapsulating.  It
>> currently doesn't.
>> 
>> Well, from implementation again, if the first thing one does is to
>> have stateless auto-config (i.e. have a real IPv6 CoA) running on
>> the UDP tunnel, then bootstrapping would work unmodified, 3776 too.
>> Otherwise I wonder how 3776 would work with IPv4 Care-of Addresses,
>> especially when there is no real IPv6 Care-of Address, especially
>> when the IPv4 CoA behind NAT, so an IPv4 address is common to two
>> nodes.
>> 
>> Alex
>>