Re: [rtcweb] JSEP-06: How to create the second offer where only the port numbers are changed?

Christer Holmberg <> Mon, 03 March 2014 10:31 UTC

Return-Path: <>
Received: from localhost ( []) by (Postfix) with ESMTP id EA70A1A0E73 for <>; Mon, 3 Mar 2014 02:31:06 -0800 (PST)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -3.85
X-Spam-Status: No, score=-3.85 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, HELO_EQ_SE=0.35, HTML_MESSAGE=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 HzysHfXvtkDX for <>; Mon, 3 Mar 2014 02:31:04 -0800 (PST)
Received: from ( []) by (Postfix) with ESMTP id 1A02B1A0E72 for <>; Mon, 3 Mar 2014 02:31:03 -0800 (PST)
X-AuditID: c1b4fb25-b7f038e000005d01-2e-531459e4c910
Received: from (Unknown_Domain []) by (Symantec Mail Security) with SMTP id FD.15.23809.4E954135; Mon, 3 Mar 2014 11:31:00 +0100 (CET)
Received: from ([]) by ([]) with mapi id 14.02.0387.000; Mon, 3 Mar 2014 11:30:59 +0100
From: Christer Holmberg <>
To: Justin Uberti <>
Thread-Topic: JSEP-06: How to create the second offer where only the port numbers are changed?
Thread-Index: Ac8xgmHR3mZq1KQqQbqrDgGDhayzRAE1nSgAABypJXA=
Date: Mon, 03 Mar 2014 10:30:59 +0000
Message-ID: <>
References: <> <>
In-Reply-To: <>
Accept-Language: en-US
Content-Language: en-US
x-originating-ip: []
Content-Type: multipart/alternative; boundary="_000_7594FB04B1934943A5C02806D1A2204B1D1C5BDEESESSMB209erics_"
MIME-Version: 1.0
X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFnrELMWRmVeSWpSXmKPExsUyM+Jvje6TSJFgg4+rdS22ThWyWPuvnd2B yWPBplKPJUt+MgUwRXHZpKTmZJalFunbJXBl/Hl0lqXgmF3FogtTWRoYn9h0MXJySAiYSNw/ +oUZwhaTuHBvPVsXIxeHkMAhRok3h3ezQDiLGSU6T/0Dcjg42AQsJLr/aYM0iAioSTyctYsV xGYWUJe4s/gcO4gtLBAv8fXmQyaImgSJdZ+ms0DYVhJTNl0Fq2ERUJF4c6gfbDGvgK/E2l13 mCB2TWGU2DJrOlgRp0CgxPLrz8BsRqDrvp9awwSxTFzi1pP5TBBXC0gs2XMe6gNRiZeP/7FC 2EoSi25/hqrPl2i6+YwRYpmgxMmZT1gmMIrOQjJqFpKyWUjKZgG9zCygKbF+lz5EiaLElO6H 7BC2hkTrnLnsyOILGNlXMbLnJmbmpJcbbWIExtPBLb9VdzDeOSdyiFGag0VJnPfDW+cgIYH0 xJLU7NTUgtSi+KLSnNTiQ4xMHJxSDYwzRFqUH64oTW5UeLhiq+9f7913PLvz4hWLbv6vUd76 qnx18L39tfoCPhOW+t2J45UKCGdSM31iqfv3As/DfU4r5h3Ja0u74nldqc3NUSjl41dbZ1ax Bxu8Yk6aFchdabsbIabylEfL2XKaFp9JcaVK/ikGbb+W+UdOKX6K42+yMV+au32isRJLcUai oRZzUXEiAGZMj2d1AgAA
Cc: "" <>
Subject: Re: [rtcweb] JSEP-06: How to create the second offer where only the port numbers are changed?
X-Mailman-Version: 2.1.15
Precedence: list
List-Id: Real-Time Communication in WEB-browsers working group list <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Mon, 03 Mar 2014 10:31:07 -0000

As specified in BUNDLE, before the remote peer has indicated support of BUNDLE, all m- lines (including those within to a bundle group) must have unique port numbers.
Then, when the remote peer has indicated support of BUNDLE, a second offer (called the BAS offer) needs to be sent, in which the same port number is assigned to all m- lines within a bundle group.
My question is: how do I create the BAS offer? I don’t want to change anything – I just want to get an SDP with the BUNDLE port assigned to all m- lines. Is there a flag in createOffer() for that?
The implementation knows that any offers that are created after the BUNDLE answer should have the same port numbers. So, the app could push the createOffer button once it receives the answer if it wanted to ensure this happened immediately. Otherwise, there will be an onnegotiationneeded event once ICE completes, and the offer sent at that time will have the updated ports.

When I call createOffer(), can I be ensure that only the port values will change?