Re: [Gen-art] Genart LC review: draft-ietf-avtext-rtp-grouping-taxonomy-06

Magnus Westerlund <> Mon, 18 May 2015 09:38 UTC

Return-Path: <>
Received: from localhost ( []) by (Postfix) with ESMTP id 10D2B1A8853; Mon, 18 May 2015 02:38:26 -0700 (PDT)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -2.302
X-Spam-Status: No, score=-2.302 tagged_above=-999 required=5 tests=[BAYES_40=-0.001, RCVD_IN_DNSWL_MED=-2.3, SPF_PASS=-0.001] autolearn=ham
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id rW9wQZjFLP4M; Mon, 18 May 2015 02:38:24 -0700 (PDT)
Received: from ( []) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by (Postfix) with ESMTPS id 252001A884D; Mon, 18 May 2015 02:38:22 -0700 (PDT)
X-AuditID: c1b4fb2d-f794d6d000004501-c2-5559b30d916d
Received: from (Unknown_Domain []) by (Symantec Mail Security) with SMTP id BB.37.17665.D03B9555; Mon, 18 May 2015 11:38:21 +0200 (CEST)
Received: from [] ( by ( with Microsoft SMTP Server id; Mon, 18 May 2015 11:38:02 +0200
Message-ID: <>
Date: Mon, 18 May 2015 11:38:02 +0200
From: Magnus Westerlund <>
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:31.0) Gecko/20100101 Thunderbird/31.6.0
MIME-Version: 1.0
To: Robert Sparks <>, General Area Review Team <>,, "" <>,
References: <>
In-Reply-To: <>
Content-Type: text/plain; charset="utf-8"; format="flowed"
Content-Transfer-Encoding: 8bit
X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFlrFLMWRmVeSWpSXmKPExsUyM2J7lC7v5shQgyNdYhYf791gtZjbf4PZ 4uqrzywWzzbOZ7G4NqeRzYHVY8mSn0wes3Y+YQlgiuKySUnNySxLLdK3S+DKmDVjNnvBLb6K j6tWsDcwvuHuYuTkkBAwkbjd9Z8NwhaTuHBvPZDNxSEkcIRRon3vCkYIZzmjxPHzxxhBqngF NCVO9/9gBbFZBFQl9s3ezwxiswlYSNz80Qg2SVQgSmLi10MsEPWCEidnPmEBGSQicJBRYumx +WCDhAU8JU7sXgdWJCSgJbFxxl+wOKeAtsTp6QvBbGagoTPnn4ey5SWat85mhqjXlmho6mCd wCgwC8mOWUhaZiFpWcDIvIpRtDi1uDg33chYL7UoM7m4OD9PLy+1ZBMjMHAPbvmtu4Nx9WvH Q4wCHIxKPLwJ/JGhQqyJZcWVuYcYpTlYlMR5vbpCQoUE0hNLUrNTUwtSi+KLSnNSiw8xMnFw SjUwlpnv3xDis9AzNeLG2y+pG/56K87tkS9reyF16cxmyc0Ob8XW+CQx7fP48NQ+kuFfQ8xl i9gFubcc6gW1Wfn39sX73DV0bp24g9vuhoPy7QTW4IKpln858zZpN9hGbmI93czxYu7ZtK+N 8S+WWd4SOPlJp2ryTtvYrI0zU/afFPRmTvok/eiXEktxRqKhFnNRcSIAr7wqQz0CAAA=
Archived-At: <>
Subject: Re: [Gen-art] Genart LC review: draft-ietf-avtext-rtp-grouping-taxonomy-06
X-Mailman-Version: 2.1.15
Precedence: list
List-Id: "GEN-ART: General Area Review Team" <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Mon, 18 May 2015 09:38:26 -0000

Robert Sparks skrev den 2015-05-14 21:21:

> Major issues:
> I'm surprised that there is no mention of how SRTP fits into the
> vocabulary this
> document builds. Would it be a mistake for someone to think of SRTP as what
> this document calls a transformation? Are there any consequences of
> using SRTP
> on one or more of the streams being associated that impact how you would
> talk about
> the association? (There are certainly consequences about which elements
> can see
> into the various streams).

Yes, encryption is clearly a transformation. And there are cases where 
the order of the encryption and other transformations, like FEC, do 
matter. Thus, I agree that it is an significant oversight to not include 

So SRTP is an Securing / Protection (as it is not only Encryption) 
transformation that operates on Source RTP Streams or Redundancy RTP 
Streams to create Secured Source RTP Streams or Secured Redundancy RTP 

If one looks on something like ISMAcrypt that operates on a special form 
of packetized encoded streams, i.e. payload created, but not RTP 
headers, we get into further distinctions that we so far haven't needed 
to have.

I don't know how well we must ensure that something like ISMAcrypt is 
clearly defined, because then we do need to split the RTP packetization 
transformation into two parts.


Magnus Westerlund

Services, Media and Network features, Ericsson Research EAB/TXM
Ericsson AB                 | Phone  +46 10 7148287
Färögatan 6                 | Mobile +46 73 0949079
SE-164 80 Stockholm, Sweden | mailto: