Subject: Re: [AVT] An optional a=rtp-keepalive SDP attribute?

From: Tom Taylor <[email-masked]>
Date: Thu, 02 Oct 2008 11:07:25 -0400

It's time this got closed off. Since there has been no comment on the MMUSIC 
list, my Chair's view is to go ahead and add the attribute.

Xavier Marjou wrote:
> Hi all,
> 
> In order to solve the remaining issue of the draft
> http://tools.ietf.org/html/draft-ietf-avt-app-rtp-keepalive-03 (cf
> details at http://www.ietf.org/mail-archive/web/avt/current/msg09656.html
> ), we would like some feedback from the MMUSIC WG.
> 
> The issue is the following: When rtcp-rtp-mux can not be negotiated,
> there is a need for an agent to send rtp-keepalive (RTP packets
> containing no media) without consulting the remote agent (ie: no need
> for offer/answer negotiation). Some people indicated they would like
> to see this feature indicated in the SDP. We would thus like to know
> whether it would be acceptable that an agent add an optional
> a=rtp-keepalive SDP attribute in order to indicate that it will send
> rtp-keepalive when rtcp-rtp can not be negotiated.
> 
> Cheers,
> Xavier
> 
> 
_______________________________________________
Audio/Video Transport Working Group
[email-masked]
https://www.ietf.org/mailman/listinfo/avt

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From: "Xavier Marjou" <[email-masked]>
Date: Thu, 2 Oct 2008 18:04:19 +0200

We, authors, have just submitted a new version. A
draft-ietf-avt-app-rtp-keepalive-04 should appear soon on the AVT WG
list.
This version includes the parameter discussed below, as well as all
the other comments received during the WGLC.

Cheers,
Xavier

On Thu, Oct 2, 2008 at 5:07 PM, Tom Taylor <[email-masked]> wrote:
> mmusic mailing list
> [email-masked]
> https://www.ietf.org/mailman/listinfo/mmusic
>

---

From: Tom Taylor <[email-masked]>
Date: Thu, 02 Oct 2008 12:12:52 -0400

If no further comments are received by 9 October 2008, this will be forwarded to 
the IESG.

---

From: Colin Perkins <[email-masked]>
Date: Mon, 20 Oct 2008 18:42:09 +0100

[Apologies for the late response]

I have no objections to the idea of an SDP attribute to indicate that  
keep-alive packets will be generated, but this particular attribute  
seems under-specified. In particular, I think the draft needs to  
spell out exactly what is included in the offer, and what response  
results in multiplexed RTCP and RTP packets being used as the keep- 
alive, versus which results in using RTP packets with invalid payload  
type as the keep-alive.

I assume the offer should include both the "a=rtcp-mux" and "a=rtp- 
keepalive" attributes, and send RTCP packets being multiplexed on the  
RTP port as a keep-alive if the "a=rtcp-mux" attribute is present in  
the answer, and RTP packets with an invalid payload type otherwise,  
but this should be spelt out.

Colin

On 2 Oct 2008, at 17:12, Tom Taylor wrote:
> If no further comments are received by 9 October 2008, this will be  
> forwarded to the IESG.
>
> Xavier Marjou wrote:

-- 
Colin Perkins
http://csperkins.org/

---

From: "Xavier Marjou" <[email-masked]>
Date: Wed, 22 Oct 2008 09:54:10 +0200

We propose to add the following sentence at the end of
http://tools.ietf.org/html/draft-ietf-avt-app-rtp-keepalive-04#section-5 :

When using the SDP [RFC3264] offer-answer, the agent SHOULD offer both
the "a=rtcp-mux" and "a=rtp-keepalive" attributes. If "a=rtcp-mux"
attribute is present in the answer, the agent uses RTCP packets being
multiplexed on the RTP port as a keepalive. Otherwise, the agent uses
RTP packets with an invalid  payload type as a keepalive.

Cheers,
Xavier

On Mon, Oct 20, 2008 at 7:42 PM, Colin Perkins <[email-masked]> wrote:
> keep-alive packets will be generated, but this particular attribute seems
> under-specified. In particular, I think the draft needs to spell out exactly
> what is included in the offer, and what response results in multiplexed RTCP
> and RTP packets being used as the keep-alive, versus which results in using
> RTP packets with invalid payload type as the keep-alive.
>
> I assume the offer should include both the "a=rtcp-mux" and
> "a=rtp-keepalive" attributes, and send RTCP packets being multiplexed on the
> RTP port as a keep-alive if the "a=rtcp-mux" attribute is present in the
> answer, and RTP packets with an invalid payload type otherwise, but this
> should be spelt out.
>
> Colin
>
>
>
>
>>>>> details at
>>>>> http://www.ietf.org/mail-archive/web/avt/current/msg09656.html

---

From: Colin Perkins <[email-masked]>
Date: Wed, 22 Oct 2008 09:00:40 +0100

Looks good to me.
Colin

On 22 Oct 2008, at 08:54, Xavier Marjou wrote:
>>>>> It's time this got closed off. Since there has been no comment  
>>>>> on the
>>>>> MMUSIC

-- 
Colin Perkins
http://csperkins.org/