Subject: [MMUSIC] draft-dtls-sdp: making SDP dtls-id attribute value globally unique

From: Christer Holmberg <[email-masked]>
Date: Wed, 23 Nov 2016 13:25:47 +0000

Hi,

Currently, draft-dtls-sdp defines that each endpoint defines a value (let’s call it X) that is a combination of the local fingerprint value and dtls-id value. The pair of X values (offerer and answerer) then identifies the DTLS association.

Some people have recently reviewed the draft, prior to publication request, and the procedures above seem to be difficult to understand - no matter how we have tried to clarify and re-word them.

Therefore, the authors suggest to mandate the dtls-id value globally unique (similar to ICE ufrags), and only the pair of dtls-id values (offerer and answerer) would then identity the DTLS associations (naturally, a change of fingerprint would still require a new DTLS association).

In addition, when an endpoint wants to create a new DTLS association, it always has to create a new local dtls-id value. Currently that is not needed if the fingerprint is changed, and people have had difficulties to understand that too.

So, we believe that the change to make the dtls-id value globally unique will make the procedures much easier and straight forward.

Regards,

Christer