Re: [rtcweb] New Version Notification for draft-jesup-rtcweb-data-01.txt

Eric Rescorla <ekr@rtfm.com> Fri, 11 November 2011 14:52 UTC

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From: Eric Rescorla <ekr@rtfm.com>
Date: Fri, 11 Nov 2011 06:51:23 -0800
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To: Michael Tuexen <Michael.Tuexen@lurchi.franken.de>
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Cc: "rtcweb@ietf.org" <rtcweb@ietf.org>
Subject: Re: [rtcweb] New Version Notification for draft-jesup-rtcweb-data-01.txt
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On Fri, Nov 11, 2011 at 5:15 AM, Michael Tuexen
<Michael.Tuexen@lurchi.franken.de> wrote:
> Hi Michael,
>>  o DTLS and SCTP handshakes must be performed serially (no matter which order they happen in), which increases the number of round-trips necessary to establish communication.
> That is correct. SCTP adds one RTT to whatever DTLS is requiring.
> So when using SCTP/DTLS/UDP, DTLS needs 3 RTTs (including the initial
> RTT required for the Cookie exchange).
> When using DTLS/SCTP/UDP DTLS needs 2 RTTs (since there is no need for
> the DTLS Cookie).

There's no need for the DTLS cookie in either case, actually, since ICE provides
the appropriate proof of return routability.

Also, DTLS should probably be used with False Start here, so you can reduce
to one RTT.

-Ekr