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From: Michael Tuexen <Michael.Tuexen@lurchi.franken.de>
In-Reply-To: <39821B4C400EC14DAD4DB25330A9271A0191D3@FR711WXCHMBA03.zeu.alcatel-lucent.com>
Date: Mon, 4 Mar 2013 19:46:37 +0100
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Message-Id: <085532B8-9A37-44D6-B311-14AFEBDF5221@lurchi.franken.de>
References: <20130225224014.18570.20111.idtracker@ietfa.amsl.com>
 <39821B4C400EC14DAD4DB25330A9271A0191D3@FR711WXCHMBA03.zeu.alcatel-lucent.com>
To: "MARCON, JEROME (JEROME)" <jerome.marcon@alcatel-lucent.com>
Cc: Randell Jesup <randell-ietf@jesup.org>, "rtcweb@ietf.org" <rtcweb@ietf.org>
Subject: Re: [rtcweb] I-D Action: draft-ietf-rtcweb-data-channel-04.txt
Precedence: list

On Mar 4, 2013, at 3:36 PM, MARCON, JEROME (JEROME) wrote:

>=20
> Randell,
>=20
> Thanks for this update. There are some points not (yet) explained in =
the text:
>=20
> 1. Following the SDP opening handshake, are the data channels =
implicitly opened, or does the offerer send one DATA_CHANNEL_OPEN =
message per new data channel ?
>=20
> 2. "channel is available to send as soon as the DATA_CHANNEL_OPEN has =
been sent". And the SACK received I guess ?
The SACK is an SCTP level ack. So you only know that the SCTP stack of =
the peer has received it,
so you don't know if the application has received it or even processed =
it. So if you want some
sort of ack, you need an application level ack. This was done in the 3 =
way handshake stuff which
was in the older version.

In this version, the sender sends an DATA_CHANNEL_OPEN as the first =
message and the receiver has
to buffer user messages until the DATA_CHANNEL_OPEN message has been =
received in case of reordering
in the network and using unordered delivery for user messages.

Best regards
Michael
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> 3. Assuming an endpoint creating a new offer (e.g. to reflect a change =
in media streams) while an SCTP association is already established. In =
this case, what does the SCTP association m-line contain: the unchanged =
list of data channels contained in the initial offer (which created the =
SCTP association), or the list of data channels currently opened, or .. =
?
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> 4. What happens if the SDP Opening Handshake agreed on some data =
channels using the 'chat' subprotocol, and later on an endpoint creates =
in-band a new channel with 'file transfer' subprotocol ?
>=20
> Jerome
>=20
>> -----Message d'origine-----
>> De : rtcweb-bounces@ietf.org [mailto:rtcweb-bounces@ietf.org]=20
>> De la part de internet-drafts@ietf.org
>> Envoy=E9 : lundi 25 f=E9vrier 2013 23:40
>> =C0 : i-d-announce@ietf.org
>> Cc : rtcweb@ietf.org
>> Objet : [rtcweb] I-D Action: draft-ietf-rtcweb-data-channel-04.txt
>>=20
>>=20
>> A New Internet-Draft is available from the on-line=20
>> Internet-Drafts directories.
>> This draft is a work item of the Real-Time Communication in=20
>> WEB-browsers Working Group of the IETF.
>>=20
>> 	Title           : RTCWeb Data Channels
>> 	Author(s)       : Randell Jesup
>>                          Salvatore Loreto
>>                          Michael Tuexen
>> 	Filename        : draft-ietf-rtcweb-data-channel-04.txt
>> 	Pages           : 13
>> 	Date            : 2013-02-25
>>=20
>> Abstract:
>>   The Web Real-Time Communication (WebRTC) working group is=20
>> charged to
>>   provide protocol support for direct interactive rich communication
>>   using audio, video, and data between two peers' web-browsers.  This
>>   document specifies the non-media data transport aspects of=20
>> the WebRTC
>>   framework.  It provides an architectural overview of how the Stream
>>   Control Transmission Protocol (SCTP) is used in the WebRTC=20
>> context as
>>   a generic transport service allowing Web Browser to=20
>> exchange generic
>>   data from peer to peer.
>>=20
>>=20
>> The IETF datatracker status page for this draft is:
>> https://datatracker.ietf.org/doc/draft-ietf-rtcweb-data-channel
>>=20
>> There's also a htmlized version available at:
>> http://tools.ietf.org/html/draft-ietf-rtcweb-data-channel-04
>>=20
>> A diff from the previous version is available at:
>> http://www.ietf.org/rfcdiff?url2=3Ddraft-ietf-rtcweb-data-channel-04
>>=20
>>=20
>> Internet-Drafts are also available by anonymous FTP at:
>> ftp://ftp.ietf.org/internet-drafts/
>>=20
>> _______________________________________________
>> rtcweb mailing list
>> rtcweb@ietf.org
>> https://www.ietf.org/mailman/listinfo/rtcweb
>>=20
> _______________________________________________
> rtcweb mailing list
> rtcweb@ietf.org
> https://www.ietf.org/mailman/listinfo/rtcweb
>=20