Re: [MMUSIC] I-D Action: draft-ietf-mmusic-sdp-miscellaneous-caps-04.txt

Hadriel Kaplan <> Fri, 15 March 2013 16:53 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id A92F821F8556 for <>; Fri, 15 Mar 2013 09:53:53 -0700 (PDT)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -2.419
X-Spam-Status: No, score=-2.419 tagged_above=-999 required=5 tests=[AWL=0.180, BAYES_00=-2.599]
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id 4Vlu9UMUtbSo for <>; Fri, 15 Mar 2013 09:53:52 -0700 (PDT)
Received: from ( []) by (Postfix) with ESMTP id 1C90721F859C for <>; Fri, 15 Mar 2013 09:53:50 -0700 (PDT)
X-ASG-Debug-ID: 1363366426-03fc200f2562d190001-mNOVBD
Received: from ( []) by with ESMTP id 9TEVHaxvA0x9S2aw (version=TLSv1 cipher=AES128-SHA bits=128 verify=NO); Fri, 15 Mar 2013 12:53:46 -0400 (EDT)
Received: from ([]) by ([]) with mapi id 14.02.0283.003; Fri, 15 Mar 2013 12:53:46 -0400
From: Hadriel Kaplan <>
To: "" <>
Thread-Topic: [MMUSIC] I-D Action: draft-ietf-mmusic-sdp-miscellaneous-caps-04.txt
X-ASG-Orig-Subj: Re: [MMUSIC] I-D Action: draft-ietf-mmusic-sdp-miscellaneous-caps-04.txt
Thread-Index: AQHOIZ2oX80TZp0sXU2z/TVygd1ojw==
Date: Fri, 15 Mar 2013 16:53:45 +0000
Message-ID: <>
References: <> <> <> <>
In-Reply-To: <>
Accept-Language: en-US
Content-Language: en-US
x-originating-ip: []
Content-Type: text/plain; charset="Windows-1252"
Content-ID: <>
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
X-Barracuda-Start-Time: 1363366426
X-Barracuda-Encrypted: AES128-SHA
X-Virus-Scanned: by bsmtpd at
X-Barracuda-BRTS-Status: 1
X-Barracuda-Spam-Score: 0.00
X-Barracuda-Spam-Status: No, SCORE=0.00 using per-user scores of TAG_LEVEL=1000.0 QUARANTINE_LEVEL=1000.0 KILL_LEVEL=9.0 tests=BSF_SC0_MISMATCH_TO
X-Barracuda-Spam-Report: Code version 3.2, rules version Rule breakdown below pts rule name description ---- ---------------------- -------------------------------------------------- 0.00 BSF_SC0_MISMATCH_TO Envelope rcpt doesn't match header
Cc: " (E-mail)" <>
Subject: Re: [MMUSIC] I-D Action: draft-ietf-mmusic-sdp-miscellaneous-caps-04.txt
X-Mailman-Version: 2.1.12
Precedence: list
List-Id: Multiparty Multimedia Session Control Working Group <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Fri, 15 Mar 2013 16:53:54 -0000

That was my understanding as well - that ccap wouldn't be used to perform alternate address family selection.  However the current text doesn't clearly say that, but rather is confusing.  Mostly just because of the exact English words being used, I think.

Regardless, ccap can't really be used for alternate address selection anyway, because it doesn't indicate a port number for the ccap alternate address.  It's technically possible to use the same port number for an IP4 and IP6 interface, of course, but it's not practical for many.

But because ccap doesn't support indicating a port number, it also can't be used to indicate an IP address when the m/c= lines indicate a PSTN circuit, afaict.  Right?

If so, then why does ccap even support indicating an IP address to begin with?  Why isn't it *only* for indicating a PSTN circuit, when the m/c lines indicate an IP4 or IP6 default?  In other words, why not just change the ABNF of ccap to only support a PSTN type; or to never be for 'IP4' nor for 'IP6'.


On Mar 15, 2013, at 8:04 AM, wrote:

> I think this goes all the way back to IETF68, where an agreement was made to use ICE for future address type selection (deprecating ANAT).
> I couldn’t find a written statement in minutes on ccap being explicitly forbidden to express IP4 and/or IP6 addresses as alternatives – but my thought has been that alternative IP addresses may only be offered with ICE. This was also reflected in by Jean-Francois ( where he says ” As for proposing IPv4/IPv6 alternatives, ICE deprecates ANAT and is the preferred solution the WG has chosen so far per IETF#68. “