Subject: [MMUSIC] ICE TCP: new SDP encoding, SDP example, and candidate priority formula

From: Ari Keranen <[email-masked]>
Date: Fri, 17 Dec 2010 17:54:58 +0200

Folks,

We have now updated the ICE-TCP draft to include SDP examples and fixed 
issues based on Hadriel's review comments (e.g., changed the SDP 
encoding of TCP candidates and included ABNF of the syntax).

While working with the SDP example we noticed that the proposed 
candidate prioritization method was somewhat confusing and came up with 
a better proposal. Instead of coding UDP-tunneled and NAT-assisted types 
in the "local preference" part, we propose to encode them in them in the 
type part and also do prioritization between transport protocols using 
the type part of the formula. This made the calculation simpler and 
allows for more flexibility when defining whether certain transport 
protocol or certain candidate type should be preferred. See Section 4.2. 
for details.

We'd like to ask for WG feedback on the new method (and other changes) 
before submitting a new version to the ID tracker. Meanwhile, updated 
draft can be found here:
http://users.piuha.net/akeranen/drafts/draft-ietf-mmusic-ice-tcp-12.txt

Diff against the previous version is available here:
http://users.piuha.net/akeranen/drafts/draft-ietf-mmusic-ice-tcp-12-diff.html

We also got off-list feedback that the "45% success ratio" is somewhat 
outdated and applies to only one of the possible techniques and updated 
the text in Appendix A accordingly.

Cheers,
Ari

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From: Simon Perreault <[email-masked]>
Date: Fri, 17 Dec 2010 11:13:54 -0500

> the text in Appendix A accordingly.

This is great news!

How could this be explained? I can only guess that the prevalence of
UPnP and NAT-PMP would have increased.

Simon
-- 
DTN made easy, lean, and smart --> http://postellation.viagenie.ca
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From: Ari Keranen <[email-masked]>
Date: Mon, 20 Dec 2010 10:30:25 +0200

> UPnP and NAT-PMP would have increased.

The "45% success ratio" was only for the simultaneous-open technique, so 
if you add just about any other technique (e.g., UPnP and NAT-PMP), 
you'll increase the success ratio. Also, if you use UDP-tunneling (e.g., 
Teredo), you'll naturally get much higher success ratio. Basically, the 
problem with the original text was that some got the impression that 45% 
would apply to the whole ICE TCP.

Cheers,
Ari

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From: Simon Perreault <[email-masked]>
Date: Mon, 20 Dec 2010 11:14:09 -0500

> would apply to the whole ICE TCP.

Right. The ratio that is interesting is the one that includes the
methods that don't involve a relay: STUN, NAT-PMP, UPnP, TCP over UDP,
etc. This is what's called "success". Using a relay is "failure". And if
you cannot even use a relay, that's "miserable failure". ;)

Simon

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From: Ari Keranen <[email-masked]>
Date: Tue, 21 Dec 2010 13:33:55 +0200

FYI, there was a small bug with the TCP candidate priority values of the 
SDP example. I just generated a new version of the draft and the diff 
and uploaded them to the same place as before (see below).

Also, still looking for feedback on the new priority formula.

Cheers,
Ari

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From: Ari Keranen <[email-masked]>
Date: Tue, 21 Dec 2010 13:38:54 +0200

> you cannot even use a relay, that's "miserable failure". ;)

Exactly :)

Cheers,
Ari