Re: [AVTCORE] Fwd: I-D Action: draft-perkins-avtcore-rtp-circuit-breakers-00.txt
Mark Handley <M.Handley@cs.ucl.ac.uk> Wed, 04 April 2012 01:55 UTC
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From: Mark Handley <M.Handley@cs.ucl.ac.uk>
Date: Wed, 04 Apr 2012 02:55:32 +0100
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To: Colin Perkins <csp@csperkins.org>
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Cc: rtp-congestion@alvestrand.no, "avt@ietf.org WG" <avt@ietf.org>
Subject: Re: [AVTCORE] Fwd: I-D Action: draft-perkins-avtcore-rtp-circuit-breakers-00.txt
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Colin, Varun, Can you clarify how the circuit breaker mechanism would work with RFC 4585 extended feedback. To make things concrete, I'm thinking about the following scenario: - Sender is sending 2Mb/s video into a 4Mb/s DSL line. RTT is 100ms. - Receiver is allowed to send up to 2.5% of this as RTCP feedback in ACK mode, so that's 6.5 packets per RTT if I got the maths right. - A TCP flow slowstarts, doubles the window for the last time and collides with the RTP flow in the wonderful way slowstart sometimes does. If you're unlucky, you'll get 33% packet loss for one full RTT before TCP backs off. - The RTCP receiver sends 6 successive RTCP reports over one RTT indicating 33% loss. If doesn't really matter if ACKs or NACKs are sent in this scenario. The calculated TCP rate would be ~18Kb/s for those parameters, so the circuit breaker would kick in if I understood the draft correctly because that's more than two reporting intervals with excessively high loss. This is the main reason for loss event rate in the TFRC specification - you avoid responding to such transients too strongly. Cheers, Mark On 5 March 2012 23:32, Colin Perkins <csp@csperkins.org> wrote: > Here's our initial attempt at a "circuit breakers" draft for RTCWeb. Comments welcome - this is very much a straw-man for discussion, rather than a final solution. > > Colin > > > > Begin forwarded message: >> From: internet-drafts@ietf.org >> Subject: I-D Action: draft-perkins-avtcore-rtp-circuit-breakers-00.txt >> Date: 5 March 2012 20:17:59 GMT >> To: i-d-announce@ietf.org >> Reply-To: internet-drafts@ietf.org >> >> >> A New Internet-Draft is available from the on-line Internet-Drafts directories. >> >> Title : RTP Congestion Control: Circuit Breakers for Unicast Sessions >> Author(s) : Colin Perkins >> Varun Singh >> Filename : draft-perkins-avtcore-rtp-circuit-breakers-00.txt >> Pages : 14 >> Date : 2012-03-05 >> >> The Real-time Transport Protocol (RTP) is widely used for telephony, >> video conferencing, and telepresence applications. These >> applications are often used over best-effort UDP/IP networks. If >> congestion control is not implemented then network congestion will >> deteriorate the user's multimedia experience. This document does not >> propose a congestion control algorithm. Instead, it specifies a >> minimal set of "circuit-breakers". Circuit-breakers are conditions >> under which an RTP flow should cease to transmit media to protect the >> network from excessive congestion. It is expected that all RTP >> applications running on best-effort networks will be able to run >> without triggering these circuit breakers in normal operation. >> >> >> A URL for this Internet-Draft is: >> http://www.ietf.org/internet-drafts/draft-perkins-avtcore-rtp-circuit-breakers-00.txt > > -- > Colin Perkins > http://csperkins.org/ > > > > _______________________________________________ > Audio/Video Transport Core Maintenance > avt@ietf.org > https://www.ietf.org/mailman/listinfo/avt
- Re: [AVTCORE] [R-C] Fwd: I-D Action: draft-perkin… Harald Alvestrand
- [AVTCORE] Fwd: I-D Action: draft-perkins-avtcore-… Colin Perkins
- Re: [AVTCORE] [R-C] Fwd: I-D Action: draft-perkin… Varun Singh
- Re: [AVTCORE] [R-C] Fwd: I-D Action: draft-perkin… Harald Alvestrand
- Re: [AVTCORE] [R-C] Fwd: I-D Action: draft-perkin… Varun Singh
- Re: [AVTCORE] [R-C] I-D Action: draft-perkins-avt… Colin Perkins
- [AVTCORE] rtp-circuit-breakers-00 when not using … James M. Polk
- Re: [AVTCORE] [R-C] Fwd: I-D Action: draft-perkin… Harald Alvestrand
- Re: [AVTCORE] [R-C] Fwd: I-D Action: draft-perkin… Colin Perkins
- Re: [AVTCORE] [R-C] Fwd: I-D Action: draft-perkin… Harald Alvestrand
- Re: [AVTCORE] I-D Action: draft-perkins-avtcore-r… Colin Perkins
- Re: [AVTCORE] [R-C] I-D Action: draft-perkins-avt… Varun Singh
- Re: [AVTCORE] Fwd: I-D Action: draft-perkins-avtc… Mark Handley
- Re: [AVTCORE] rtp-circuit-breakers-00 when not us… Colin Perkins