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Re: [rtcweb] Resolving RTP/SDES question in Paris

Hadriel Kaplan <HKaplan@acmepacket.com> Mon, 19 March 2012 21:36 UTC

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From: Hadriel Kaplan <HKaplan@acmepacket.com>
To: Roman Shpount <roman@telurix.com>
Thread-Topic: [rtcweb] Resolving RTP/SDES question in Paris
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Date: Mon, 19 Mar 2012 21:36:47 +0000
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Cc: "<rtcweb@ietf.org>" <rtcweb@ietf.org>
Subject: Re: [rtcweb] Resolving RTP/SDES question in Paris
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On Mar 19, 2012, at 4:08 PM, Roman Shpount wrote:

> Is there any case in which using SDES-SRTP is better then using DTLS-SRTP, except interop with old/legacy devices?


Yup.  The other advantages of SDES are:
1) Shorter call-answer-delay, because there're no additional round-trips before media other than ICE
2) Cheaper/less-overhead/better-scaling
3) Fewer interop issues - we don't know what DTLS-SRTP interop issues will exist, if any, but more code usually means more interop issues, or at least more "bugs".  ICE itself will probably have some issues anyway[*], but more code and complexity won't help matters.

And if the Identity-model stuff is mandatory to use for DTLS, you can multiply the impact of those factors by some non-zero multiple.

-hadriel
[*] There are already multiple variants of ICE in the wild, with one implementation known not to interop with others.  But I don't know if it's an SDP-specific ICE interop issue or a problem with the connectivity checks or state machine.

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