Re: [rtcweb] Network times . was SDP Security Descriptions (RFC 4568) and RTCWeb (UNCLASSIFIED)

Bo Burman <bo.burman@ericsson.com> Thu, 02 May 2013 08:18 UTC

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From: Bo Burman <bo.burman@ericsson.com>
To: "rtcweb@ietf.org" <rtcweb@ietf.org>
Thread-Topic: [rtcweb] Network times . was SDP Security Descriptions (RFC 4568) and RTCWeb (UNCLASSIFIED)
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Date: Thu, 02 May 2013 08:18:29 +0000
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Subject: Re: [rtcweb] Network times . was SDP Security Descriptions (RFC 4568) and RTCWeb (UNCLASSIFIED)
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I agree that delay-limited retransmission can be an appropriate functionality also for media. Definitely for video, but maybe also for audio. I expect that actual loss and delay requirements will depend on how media (WebRTC) is used in the specific application use case, making it hard to set one single delay requirement.

For SRTP traffic, would not RFC 4588 (RTP retransmission) provide a good start, especially since you can set a maximum feasible (re-)transmission delay limit on a per-call and per-media basis in the SDP?

/Bo B

> -----Original Message-----
> From: rtcweb-bounces@ietf.org [mailto:rtcweb-bounces@ietf.org] On Behalf Of Roy, Radhika R CIV USARMY (US)
> Sent: den 1 maj 2013 21:02
> To: Randell Jesup; rtcweb@ietf.org
> Subject: Re: [rtcweb] Network times . was SDP Security Descriptions (RFC 4568) and RTCWeb (UNCLASSIFIED)
> 
> Classification: UNCLASSIFIED
> Caveats: NONE
> 
> Inline [RRR]
> 
> -----Original Message-----
> From: rtcweb-bounces@ietf.org [mailto:rtcweb-bounces@ietf.org] On Behalf Of Randell Jesup
> Sent: Wednesday, May 01, 2013 2:19 PM
> To: rtcweb@ietf.org
> Subject: Re: [rtcweb] Network times . was SDP Security Descriptions (RFC
> 4568) and RTCWeb (UNCLASSIFIED)
> 
> On 5/1/2013 4:46 AM, Roy, Radhika R CIV USARMY (US) wrote:
> > I am responding only on a part of this email about retransmissions of
> > audio or video packets.
> >
> > Let us not consider the retransmission of audio or video packets. Let
> > us consider audio or video packets are sent only over UDP. Let MOS/QoS
> > of audio or video are considered in a way that retransmissions do not
> > take
> place.
> >
> > Then the question comes only about "data" traffic retransmissions.
> > Data traffic can tolerate much higher delays than that of audio or
> > video. Data has only QoS (and no MOS).
> 
> It may not have MOS per-se, but unreliable data channels have equivalent issues - think of a first-person realtime game -
> unreliable position/state updates of the user and the world mean that what data is lost (and how much data is delayed
> but received) has a very strong impact on the user's perception of the world.
> 
> [RRR] Yes, we need to have NEW threshold of delays (RTT) for data performance.
> --
> Randell Jesup
> randell-ietf@jesup.org
> 
> 
> 
> 
> Classification: UNCLASSIFIED
> Caveats: NONE