Subject: [MMUSIC] Yet another alternative to ICE WAS (Re: draft-ietf-mmusic-media-loopback-14 review and comments)

From: Gonzalo Camarillo <[email-masked]>
Date: Sat, 4 Dec 2010 22:33:08 +0200

Hi,

>> - NAT Traversal and usage of ICE
>>
>> [Authors] As Hadriel mentioned, if you have ICE you don’t need the
>> loopback primer. As he also clarified, the loopback situation is
>> different from standard calls because the mirror will never send a
>> packet until it receives something from the source. This is certainly
>> possible for a regular call and calls may fail for that reason, but
>> the loopback draft is dead without a solution for this problem.
>> Remember that the primary use case for this draft is service providers
>> wanting to test to subscriber devices that are almost always behind
>> NATs. The proposed solution meets the requirements for the dominant
>> use case and while standard solutions are certainly usable when they
>> are available, the unfortunate reality is that most of them are not
>> implemented. We can add clarification text that if available ICE
>> should be used instead of the loopback primer method.
>>
> Thanks. The draft will also need to clearly explain how the loopback
> primer would work, and in particular what the underlying assumptions are
> (e.g. latching) as well as when it will not work (e.g. when both source
> and mirror are behind a NAT, when you have overlapping IP-addresses and
> ports, etc). In short, the limitations of this approach must be clearly
> documented.
> 
> I will also check with our AD as to whether there are any additional
> concerns with specifying such a solution when we already have ICE as the
> Standard.

as you all know, there have been a number of proposals to standardize
simpler-than-ICE NAT traversal solutions that would only work in certain
scenarios or circumstances. There have been a lot of discussions around
them. A couple of IETFs ago there was even a bar BOF where people tried
to understand the issues that kept folks from deploying ICE in some
scenarios. I know there have been off-list follow ups on those
discussions but no draft have been submitted yet, AFAIK.

So, we need to frame this discussion taking into account the big picture
of NAT traversal and ICE. In this case, we need to understand the issues
that keep ICE from being widely deployed and, if needed, specify a
general solution to address those issues. Coming up with several
different NAT traversal mechanisms that only work in specific conditions
does not seem like the best outcome we can wish for.

I encourage people who are working on those ICE-related issues to
participate in this discussion because this is an important area.

Thanks,

Gonzalo