Re: [MMUSIC] Draft new version: draft-holmberg-mmusic-sdp-dtls-01

Salvatore Loreto <salvatore.loreto@ericsson.com> Mon, 22 June 2015 09:51 UTC

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From: Salvatore Loreto <salvatore.loreto@ericsson.com>
To: Christer Holmberg <christer.holmberg@ericsson.com>, Martin Thomson <martin.thomson@gmail.com>
Thread-Topic: [MMUSIC] Draft new version: draft-holmberg-mmusic-sdp-dtls-01
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Date: Mon, 22 Jun 2015 09:51:04 +0000
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Cc: "mmusic@ietf.org" <mmusic@ietf.org>, Paul Kyzivat <pkyzivat@alum.mit.edu>
Subject: Re: [MMUSIC] Draft new version: draft-holmberg-mmusic-sdp-dtls-01
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> On 21 Jun 2015, at 01:05, Christer Holmberg <christer.holmberg@ericsson.com> wrote:
> 
> Hi Paul,
> 
> Thanks for your comments. See inline.
> 
> 
>> * Section 2.1:
>> 
>>   When a new DTLS association is established, an endpoint MUST use a
>>   new set of transport parameters (IP address and port combination).
>> 
>> The above seems slightly ambiguous: does "an endpoint" mean "each endpoint" or "one (of the two) endpoints"?
>> 
>> IIUC we have established that the important point is that the 5-tuple must change. So at least one side must change the address or port. But if one > side is known to do so, then the other side need not do so. So I suggest changing the above to:
>> 
>>   When a new DTLS association is established, one of the endpoints
>>   MUST use a new set of transport parameters (IP address and port
>>   combination).
> 
> The idea is that the endpoint(s) which does something the requires a new set of transport parameters needs to use a new set.
> 
> So, if e.g. endpoint A wants to change the fingerprint, which requires a new DTLS association, endpoint A needs to use a new set of transport parameters.

I agree that
If you change the certificate you intend to use, then you need a new DTLS association

however I am not sure that this (i.e. the change of the certificate) also implies the endpoint has to use necessary a new set of transport parameters.

Can you someone clarify this to me?

thanks 
/Sal