Re: [Dart] DART dscp-rtp draft: Proposed RTCP text
Ben Campbell <ben@nostrum.com> Thu, 28 August 2014 20:44 UTC
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From: Ben Campbell <ben@nostrum.com>
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Date: Thu, 28 Aug 2014 15:44:44 -0500
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To: "Black, David" <david.black@emc.com>
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Cc: "dart@ietf.org" <dart@ietf.org>, "avt@ietf.org WG (avt@ietf.org)" <avt@ietf.org>, "Colin Perkins (csp@csperkins.org)" <csp@csperkins.org>
Subject: Re: [Dart] DART dscp-rtp draft: Proposed RTCP text
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That works for me, thanks! On Aug 28, 2014, at 3:36 PM, Black, David <david.black@emc.com> wrote: > Minor edit to proposed text below: > > OLD > If an RTCP sender doesn't send any RTP > packets, it should mark its RTCP packets with the DSCP that it would > use if it did send RTP packets. > NEW > If an RTCP sender doesn't send any RTP > packets, it should mark its RTCP packets with the DSCP that it would > use if it did send RTP packets with media similar to the RTP traffic > that it receives. > > Thanks, > --David > > >> -----Original Message----- >> From: Black, David >> Sent: Thursday, August 28, 2014 3:45 PM >> To: dart@ietf.org; avt@ietf.org WG (avt@ietf.org) >> Cc: Black, David; Colin Perkins (csp@csperkins.org); ben@nostrum.com >> Subject: DART dscp-rtp draft: Proposed RTCP text >> >> Here's the proposed new section 5.4, with the RTCP multi-stream reporting >> optimizations text moved into that new section from its current location >> at the end of 5.3, plus the rewritten Section 6 guideline bullet: >> >> 5.4. DiffServ and RTCP >> >> The RTP Control Protocol (RTCP) [RFC3550] is used with RTP to monitor >> quality of service and convey information about RTP session >> participants. A sender of RTCP packets that also sends RTP packets >> (i.e., originates an RTP stream) should use the same DSCP marking for >> both types of packets. If an RTCP sender doesn't send any RTP >> packets, it should mark its RTCP packets with the DSCP that it would >> use if it did send RTP packets. If the RTCP sender uses or would use >> multiple DSCPs that differ only in drop precedence for RTP, then it >> should use the DSCP with the least likelihood of drop for RTCP to >> increase the likelihood of RTCP packet delivery. >> >> This guidance may result in different DSCP markings for RTP streams >> and RTCP receiver reports about those RTP streams. The resulting >> variation in network QoS treatment by traffic direction could result >> in unrepresentative round trip time (RTT) estimates that don't >> correspond to consistent network QoS treatment in both directions. >> RTCP receiver reports may be relatively infrequent (e.g., may be sent >> only once per video frame rendered) and hence the resulting RTT >> estimates are of limited utility for congestion control (although >> they have other important uses, see [RFC3550]). For this reason, it >> is not important that RTCP receiver reports receive the same network >> QoS treatment as the RTP stream or streams being reported on. >> >> RTCP multi-stream reporting optimizations for an RTP session >> [I-D.ietf-avtcore-rtp-multi-stream-optimisation] assume that the RTP >> streams involved experience the same network behavior, including >> packet loss. This mechanism is highly inappropriate when the RTP >> streams involved use different DSCPs, even if the corresponding PHBs >> differ solely in drop precedence. >> >> 6. Guidelines >> >> [... snip ...] >> >> o Should use a single DSCP for RTCP packets, which should be a DSCP >> used for RTP packets that are or would be sent by the same sender, >> see Section 5.4. >> >> Thanks, >> --David >> ---------------------------------------------------- >> David L. Black, Distinguished Engineer >> EMC Corporation, 176 South St., Hopkinton, MA 01748 >> +1 (508) 293-7953 FAX: +1 (508) 293-7786 >> david.black@emc.com Mobile: +1 (978) 394-7754 >> ---------------------------------------------------- >> >
- [Dart] DART dscp-rtp draft: Proposed RTCP text Black, David
- Re: [Dart] DART dscp-rtp draft: Proposed RTCP text Black, David
- Re: [Dart] DART dscp-rtp draft: Proposed RTCP text Ben Campbell
- Re: [Dart] DART dscp-rtp draft: Proposed RTCP text Colin Perkins
- Re: [Dart] DART dscp-rtp draft: Proposed RTCP text Black, David