Re: [MMUSIC] Draft new: draft-holmberg-mmusic-t140-usage-data-channel

Paul Kyzivat <pkyzivat@alum.mit.edu> Fri, 23 August 2019 14:26 UTC

Return-Path: <pkyzivat@alum.mit.edu>
X-Original-To: mmusic@ietfa.amsl.com
Delivered-To: mmusic@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 57A731200C1 for <mmusic@ietfa.amsl.com>; Fri, 23 Aug 2019 07:26:31 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -4.199
X-Spam-Level:
X-Spam-Status: No, score=-4.199 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id rAllb7HQsKXb for <mmusic@ietfa.amsl.com>; Fri, 23 Aug 2019 07:26:28 -0700 (PDT)
Received: from outgoing-alum.mit.edu (outgoing-alum.mit.edu [18.7.68.33]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 6E67C1200EF for <mmusic@ietf.org>; Fri, 23 Aug 2019 07:26:21 -0700 (PDT)
Received: from Kokiri.localdomain (c-24-62-227-142.hsd1.ma.comcast.net [24.62.227.142]) (authenticated bits=0) (User authenticated as pkyzivat@ALUM.MIT.EDU) by outgoing-alum.mit.edu (8.14.7/8.12.4) with ESMTP id x7NEQJD4006933 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=NOT) for <mmusic@ietf.org>; Fri, 23 Aug 2019 10:26:20 -0400
To: mmusic@ietf.org
References: <49749CEF-41E8-4E87-8CC6-938DBDA0CEE7@ericsson.com> <CAOW+2duTuUc8FXT-BEhJioUnPsOkzYJddK=xAp1oWiBQCKM2vg@mail.gmail.com> <HE1PR07MB3161874ED292FA17015EF95E93AE0@HE1PR07MB3161.eurprd07.prod.outlook.com> <665185b6-c1e7-62c3-4e3b-e9374d23bfd5@omnitor.se> <DF010721-81CD-40DE-A848-DE4D36836FDA@ericsson.com> <ED158CF5-E059-482B-8D7E-934BA2C753A1@ericsson.com> <2201665d-5054-1872-d208-a0fe2d26095c@omnitor.se> <VI1PR07MB3167055C995D17D4BA9E36DE93A50@VI1PR07MB3167.eurprd07.prod.outlook.com> <8d14b055-8405-4a4f-174d-d7580bea348c@omnitor.se> <0DA1248C-41FC-4155-A578-29A19883857C@ericsson.com> <a91850b9-6e86-058f-dddd-3f856bcd6710@omnitor.se>
From: Paul Kyzivat <pkyzivat@alum.mit.edu>
Message-ID: <3c5cf655-2a0c-718c-a2f3-23baabfec786@alum.mit.edu>
Date: Fri, 23 Aug 2019 10:26:19 -0400
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:60.0) Gecko/20100101 Thunderbird/60.8.0
MIME-Version: 1.0
In-Reply-To: <a91850b9-6e86-058f-dddd-3f856bcd6710@omnitor.se>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 8bit
Archived-At: <https://mailarchive.ietf.org/arch/msg/mmusic/9gH5-rqn8OO7NvuD2sfikkBGefc>
Subject: Re: [MMUSIC] Draft new: draft-holmberg-mmusic-t140-usage-data-channel
X-BeenThere: mmusic@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Multiparty Multimedia Session Control Working Group <mmusic.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/mmusic>, <mailto:mmusic-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/mmusic/>
List-Post: <mailto:mmusic@ietf.org>
List-Help: <mailto:mmusic-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/mmusic>, <mailto:mmusic-request@ietf.org?subject=subscribe>
X-List-Received-Date: Fri, 23 Aug 2019 14:26:32 -0000

Gunnar,

What is the source for these requirements?

	Thanks,
	Paul

On 8/23/19 8:51 AM, Gunnar Hellström wrote:
> I hope I can stop introducing new topics soon, and contribute to 
> resolving them instead... But another topic to cover is multi-party 
> session support.  The requirement is:
> 
>     U-C 5:  Realtime text chat during an audio and/or video call with an
>             individual or with multiple people in a conference.
> 
> I hope that will be straightforward.
> 
> /Gunnar
> 
> 
> 
> Den 2019-08-23 kl. 12:09, skrev Christer Holmberg:
>> Hi,
>>
>>>>> I want to add one issue for the security section: Can we specify a way to achieve end-to-end encryption of T.140
>>>>> data between a WebRTC endpoint and a traditional SIP/RFC 4103 endpoint through a gateway? I know that that is a
>>>>> desired feature.
>>>> How would you do that? The data channel uses DTLS encryption, and SIP/RFC 4103 uses SRTP encryption, so
>>>> doesn't the gateway have to decrypt/encrypt the T.140 traffic?
>>>     
>>>     I have just heard the requirement to have end-to-end encryption of RTT,
>>>     I do not have the solution. One possibility would maybe be to have media
>>>     encryption end-to-end as well as the two transport encryptions. But that
>>>     complicates the possibility to insert the missing text markers by the
>>>     gateway if text loss is detected.
>>    
>> Yes.
>>
>> However, keep in mind that the scope of the draft is how to use SDP O/A to negotiate a T.140 WebRTC data channel. We DO include some text regarding interworking with SIP/RFC 4103, because we know there are environments where such interworking takes place.
>>
>> But, extending T.140 and/or RFC 4103 (e.g., defining a new application level encryption mechanism for T.140) is outside the scope.
>>
>> Regards,
>>
>> Christer
>>
>>
>>
>>      >
>>      >
>>      > Den 2019-08-22 kl. 16:28, skrev Christer Holmberg:
>>      >> I have created a pull request, which will be used for the changes based on Gunnar's comments:
>>      >>
>>      >>https://protect2.fireeye.com/url?k=f453465c-a88743e3-f45306c7-868f633d
>>      >> bf25-4deb49c05b8a2375&q=1&u=https%3A%2F%2Fgithub.com%2Fcdh4u%2Fdraft-d
>>      >> atachannel-t140%2Fpull%2F5
>>      >>
>>      >> Regards,
>>      >>
>>      >> Christer
>>      >>
>>      >> On 22/08/2019, 13.39, "mmusic on behalf of Christer Holmberg"<mmusic-bounces@ietf.org on behalf of christer.holmberg@ericsson.com>;  wrote:
>>      >>
>>      >>       Hi Gunnar,
>>      >>
>>      >>       Thanks you for your support (I assume :) and comments on the draft!
>>      >>
>>      >>       See inline.
>>      >>
>>      >>       >A couple of comments:
>>      >>       >1) In 3.2, the attribute "cps" is misspelled "cpc" once.
>>      >>
>>      >>       Will fix.
>>      >>
>>      >>       ---
>>      >>
>>      >>       >2) Section 5 has some historical references to real-time text transports that may not be of much interest anymore
>>      >>       >and instead confuse the reader, while some other more relevant transports may be added.
>>      >>
>>      >>       I took these from the schwarz draft. You probably know better
>>      >> than me which ones are relevant, so feel to suggest which one(s)
>>      >> should be removed, and which one(s) should be be added :)
>>      >>
>>      >>       >I would also like to discuss if it could be possible to have a few general recommendations on the webrtc to sip/rfc4103 case without
>>      >>       >the problems you see with having a detailed gateway section.
>>      >>
>>      >>       The second last paragraph covers some things on the media plane (out of order and loss of RTP packets) that I think are worth mentioning.
>>      >>
>>      >>       As far as SDP interworking is concerned, this draft defines the m- line for T.140 data channel, and RFC 4103 defines the m- line for T.140 RTP, and the interworking should be very straight forwards. Do you have something specific in mind regarding general recommendations?
>>      >>
>>      >>       ---
>>      >>
>>      >>       > 3) Reliability. Section 3.1 implies that the channel is used in the reliable and ordered mode. We have been discussing back and forth
>>      >>       > if that is the right choice for real-time text. I tend to think it is, but it might be useful to discuss it once again. The traditional user
>>      >>       > requirement on real-time text is that produced characters shall be presented to the receiver within one second from their creation.
>>      >>       > Modern usage in speech-to-text applications may require more rapid transmission. As I understand it, the reliable mode of the
>>      >>       > data channel may imply long periods of choked transmission in case of network problems or by influence of heavy transmission
>>      >>       > in another channel. As long as this happens only in case of network problems, I now tend to think that that might be acceptable.
>>      >>       > The effects of being forced to use an unreliable channel are so far-going so I would like to avoid that.
>>      >>       > However, the word "reliable" is misleading. A "reliable" channel is not really reliable. It can break in case of problems.
>>      >>
>>      >>       True, but "reliable" is the terminology used in both RFC 4960 (SCTP) and draft-ietf-rtcweb-data-channel.
>>      >>
>>      >>       > I think some recommendations should be inserted in section 4 about what to do when a channel breaks. The natural action
>>      >>       > would be for both sides to try to figure out what was the last T.140 data that was transmitted and received, and then try to
>>      >>       > reconnect and resume transmission if successful. If any T.140 data was lost during the break, that state should be marked
>>      >>       > by inserting the "missing data" T.140 indicator in the received stream. There needs of course also be a recommended action
>>      >>       > if it turns out to be impossible to reconnect after a low number of retries.
>>      >>
>>      >>       I can for sure add some text about that. Are there generic T.140 recommendations for failure that we can reference, or do you think there is something T.140 data channel specific?
>>      >>
>>      >>       Regards,
>>      >>
>>      >>       Christer
>>      >>
>>      >>
>>      >>       _______________________________________________
>>      >>       mmusic mailing list
>>      >>mmusic@ietf.org
>>      >>https://www.ietf.org/mailman/listinfo/mmusic
>>      >>
>>      >>
>>      > --
>>      > -----------------------------------------
>>      > Gunnar Hellström
>>      > Omnitor
>>      >gunnar.hellstrom@omnitor.se
>>      > +46 708 204 288
>>      >
>>      > _______________________________________________
>>      > mmusic mailing list
>>      >mmusic@ietf.org
>>      >https://www.ietf.org/mailman/listinfo/mmusic
>>      
>>      --
>>      -----------------------------------------
>>      Gunnar Hellström
>>      Omnitor
>>      gunnar.hellstrom@omnitor.se
>>      +46 708 204 288
>>      
>>      
>>
> -- 
> -----------------------------------------
> Gunnar Hellström
> Omnitor
> gunnar.hellstrom@omnitor.se
> +46 708 204 288
> 
> 
> _______________________________________________
> mmusic mailing list
> mmusic@ietf.org
> https://www.ietf.org/mailman/listinfo/mmusic
>