Re: [MMUSIC] Merging ICE aggressive and regular nomination (was Re: [tram] Comment on draft-williams-peer-redirect-01: might it not converge?)

Iñaki Baz Castillo <> Fri, 08 August 2014 10:49 UTC

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From: =?UTF-8?Q?I=C3=B1aki_Baz_Castillo?= <>
Date: Fri, 8 Aug 2014 12:49:34 +0200
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To: Justin Uberti <>
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Cc: Jonathan Lennox <>, mmusic <>
Subject: Re: [MMUSIC] Merging ICE aggressive and regular nomination (was Re: [tram] Comment on draft-williams-peer-redirect-01: might it not converge?)
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2014-07-31 21:08 GMT+02:00 Justin Uberti <>om>:
> As discussed earlier, DTLS does not require a separate context for each
> tuple. DTLS should be agnostic about the lower layer protocol (and we should
> probably create an errata to resolve this confusion).

Hi Justin, I agree with that (and I like that), but Chrome does not
behave in that way. My experiment:

- The server gives a UDP and TCP candidate to Chrome.

- Chrome nominates UDP (ICE stuff), sends the DTLS handshake and then media.

- Later the server closes its UDP socket, so STUN requests from Chrome
are not replied.

- At some point Chrome decides to open a TCP connection with the TCP
candidate. It also sends ICE stuff (OK).

- The problem: Chrome *sends* a new DTLS handshake over the new TCP connection.

This is wrong since the server already has a *working* and
*established* DTLS session (which as you say MUST be transport
agnostic), so the new DTLS HelloClient is ignored by the DTLS
machinery at server side and thus, media is never sent.

IMHO Chrome should not attempt a new DTLS handshake given that it was
already done before over the "ICE virtual socket". You opinion please?

BTW: Let me know if you want me to open a bug report, but I would love
having this clear :)

Iñaki Baz Castillo