RE: comments on draft-durand-v6ops-assisted-tunneling-requirement s-00 .txt

["Karim El-Malki (HF/EAB)" <karim.el-malki@ericsson.com>]

>> On Wed, 14 Apr 2004, Karim El-Malki (HF/EAB) wrote:
>>    Althought the main focus of this document is the ISP scenario,
>>    assisted tunneling is applicable in all the other scenarios:
>>    unmanaged, enterprise and 3GPP.
>>    ...
>>    In 3GPP networks, assisted tunneling can be used in the context of
>>    dual stack UE connecting to IPv6 nodes through a 3GPP network that
>>    only supports IPv4 PDP contexts [3GPP, 3.1].
>> 
>> There seems to be a contradiction when considering 3GPP networks,
>> since the customer does not have a NAT in the customer equipment
>> (i.e. mobile terminal). Therefore the tunneling can be terminated
>> within the mobile operator's network and never goes through a NAT.
>> That's a good thing since we wouldn't have to pass even more traffic
>> (v6 tunnelled traffic) through NATs in this scenario. For the same
>> reason the following consideration on ISATAP does not apply to 3GPP
>> networks (also described in the draft reference [3GPP]):
>> 
>>    7.3 ISATAP
>> 
>>    Similar considerations as Teredo, section 7.2, applies to Isatap.
>>    However, as Isatap can not work accross NAT, it is of much less
>>    interest in the framework of this document.
>> 
>> I think that to make this draft applicable to 3GPP networks some
>> substantial changes would be needed such as the removal of the NAT
>> assumption.
>
>I do not see the contradiction.
>
>The document just basically says, "we want to support all the 
>scenarios, whether it goes through a NAT or not".

A solution requiring NAT traversal will end up being very different
from one not requiring it, so it is an important point IMO.
Ths draft says that the solution must support NAT traversal, and this
feature is not applicable to 3gpp. So this requirement would
end up in a solution that is designed for something that is not
useful (and potentially a disadvantage) for 3gpp networks. I see
that as a problem.

>In the case of 3GPP, it doesn't go through NAT, but the requirements 
>are equally applicable.

I disagree. The requirement that the solution must work through NATs
is not applicable to 3GPP. The fact that the NAT traversal solution
may also happen to work in 3GPP doesn't mean it is the right thing to
be deployed there.

>On the other hand, as I read it, section 7.3 basically says "ISATAP 
>could be supported, but as it is not applicable through a NAT, it 
>would only be usable in the scenarios where there is no NAT, so it 
>might not be worth the effort plug ISATAP support in the tunnel 
>server clients/servers."

Well it says that "it is of much less interest in the framework of
this document.". This is essentially saying "not needed".
Since the document describes tunnelling requirements also applicable
to 3GPP I don't think this wording applies to ISATAP.

/Karim