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Re: New Version Notification for draft-koodli-ipv6-in-mobile-networks-02

Le 19 avr. 2010 à 20:26, Rajeev Koodli a écrit :

>> In sec 3.3, you have (asterisks added):
>>   " Hence a service provider may
>>   choose to enforce IPv6-only PDN and address assignment for their own
>>   subscribers in their Home Networks, see Figure 1.  This is feasible
>>   for the newer MNs when the provider's network is "IPv6-ready", which
>>   means the network is able to provide IPv6-only PDN support *and
>>  IPv6 - IPv4 interworking*  for Internet access."
>> 
>> I therefore understood the considered "IPv6-only" networks as having
>> DNS64-NAT64s (not as having no IPv4 connectivity at all).
>> 
> 
> It's both: no IPv4 connectivity, and IPv6 - IPv4 interworking.

OK, this is a vocabulary problem.
(To me, NAT64s provide IPv4 connectivity to hosts that are IPv6-only enabled.)

> Dual-stack deployments do not have either of these.

Here, I am confused.
In my understanding, dual stack everywhere provides IPv4 connectivity.

>>> ...
>>> I could reword the last sentence to: "For instance, if an LTE deployment is
>>> IPv6-only, a roamed 3G UMTS network may not offer IPv6 connectivity"
>> 
>> Isn't it true that the lack of IPv6 connectivity of some 3G UMTS networks is
>> independent from whether LTE networks are dual-standard or not?
>> 
> 
> Yes. However, the point here is that if an LTE deployment chooses to be
> IPv6-only, a roamed 3G network may not offer IPv6 connectivity, which means
> the home network (that offers IPv6-only service) needs to be able to provide
> IPv4 connectivity to such roamed users.

I see, and like better this way of saying it.

>>> "In summary, IPv6-only deployments should be encouraged while considering the
>>> roaming and applications issues"
>> 
>> I still can't agree on this because:
>> - The market of real IPv6-ony is too limited.
> 
> Well, someone has to start. There are arguments on why some want to do
> IPv6-only in mobile networks.

I understand the argument about a single routing family in the access network, and agree with it.
But like 6rd permits public IPv6 across IPv4-only infrastructures, reversed 6rd (say 4rd) permits to offer public IPv4 (typically port-restricted) across IPv6-only infrastructures.

Since LTE handsets are new, having in them the simple support of 4rd shouldn't be a big deal, and AFAIKT would avoid, with operators that also support 4rd all problems associated with IPv4-IPv6 translations.
It is clear that, until an easy to read and complete enough description of 4rd is available, entering into more details is difficult.
I should therefore concentrate on writing it.
    
>> - With simple additions in LTE MNs port-restricted public IPv4 addresses can
>> be made available across IPv6-only access networks, which reconciles IPv6 e2e
>> transparency and IPv4 connectivity with an IPv6-only routing plan in LTE
>> access networks. (About this, see also what I answered to Cameron Byrne in
>> http://ops.ietf.org/lists/v6ops/v6ops.2010/msg00609.html).
> 
> I understand. Making changes to MNs is another story. I reckon 3GPP would be
> a good place to bring this kind of proposal.

I do think so, very much so.
I hope we can try to proceed quickly in this direction.

>> IMHO, if your draft can be a great informational document if relieved of
>> general "encouragements" to deploy IPv6-only (at least as long as it
>> implicitly goes with DNS64-NAT64), and if noting the conflict between IPv6 e2e
>> transparency and DNS64-NAT64.
> 
> Thanks. 

> However, I do believe that there is a case for IPv6-only deployments from a
> variety of angles, including - private IPv4 address exhaustion, side effects
> of overlapped addresses etc., investments in NAT44, speedier transition to
> IPv6 and so on. This does have costs associated with it, as you point out
> above.

If you agree, we can resume the discussion when the 4rd description is available.

> It may be worthwhile to refer to NAT64+DNS64 considerations to an
> appropriate BEHAVE document?

Maybe, but your draft seems a good place to start with.

> Again, I would point out that the ID is not intending to prefer IPv6-only
> over Dual-stack. The latter is the default, the former should be a choice,
> at least for some. I will clarify..

Thanks for this discussion.
RD