Re: [rtcweb] Proposal to break the ICE impasse

Eric Rescorla <> Sat, 26 January 2019 17:23 UTC

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From: Eric Rescorla <>
Date: Sat, 26 Jan 2019 09:23:08 -0800
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To: Adam Roach <>
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Subject: Re: [rtcweb] Proposal to break the ICE impasse
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I'm not yet persuaded this is needed. The alleged need here is that there
are some ICE-implementing endpoints which will choke if they see a profile
that doesn't match any actual candidate. I recognize that this is required
by 5245, but that doesn't mean anyone ever did it. Can you please point me
to a client which would interoperate with a WebRTC endpoint with this
change that would not if you just always sent the same profile as JSEP
currently requires.


On Thu, Jan 24, 2019 at 11:12 AM Adam Roach <> wrote:

> Based on conversations in MMUSIC, as well as several offline
> conversations with interested parties, I've put together a proposed
> change to JSEP that, if accepted, will allow publication of the Cluster
> 238 documents to move forward.
> Note that this new text has no impact on existing implementations (at
> least, as far as I am able to discern), which do not currently have the
> capability of producing media sections consisting of exclusively TCP
> candidates. From that perspective, the change makes existing
> implementations no less compliant with JSEP than they were before.
> What this change does provide is both on-paper and in-the-future
> compatibility between WebRTC implementations once they finalize TCP
> candidate handling (and candidate handling in general for mid-session
> offers).
> The key insight here is that JSEP's use of ICE completely discards any
> meaning associated with the transport parameter, while SIP's use of ICE
> does not. The trivial change that I propose, which bears only on future
> WebRTC implementations -- that is, which has no as-built specification
> to point to -- allows JSEP to continue to ignore the value of the
> transport parameter, while specifying that it says the right thing for
> SIP implementations to function properly.
> /a
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