Re: [Dart] [rtcweb] Fwd: WGLC: draft-ietf-dart-dscp-rtp-02
Dave Taht <dave.taht@gmail.com> Wed, 13 August 2014 01:43 UTC
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From: Dave Taht <dave.taht@gmail.com>
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Subject: Re: [Dart] [rtcweb] Fwd: WGLC: draft-ietf-dart-dscp-rtp-02
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This is also of some interest to me at least, and perhaps some members of the AQM working group who are working out weighted fair queuing and wred like approaches to these needs. Anyway, I do try to track thinking in this area in the ongoing development of cerowrt's sqm system, which has pluggable modules for all the known aqm and fq schedulers, and a three tier system modeled on wondershaper for managing traffic, which uses what diffserv markings that I have observed make sense... Some relevant links: http://www.bufferbloat.net/projects/cerowrt/wiki/Wondershaper_Must_Die http://www.bufferbloat.net/projects/cerowrt/wiki/Setting_up_SQM_for_CeroWrt_310 http://www.bufferbloat.net/projects/cerowrt/wiki/Smart_Queue_Management Missing from this discussion so far is what is actually deployed out there... I am only familiar with stuff like the above as an egress/ingress queue management system... AND: in the case of linux based wireless routers, none of the AF codepoints are respected explicitly, and how the codepoints are mapped are described by 802.11e - and that is far more about scheduling priority for airtime rather than drop probability. It is kind of hard to wrap your head around how 802.11e actually works, but, this is a start: http://en.wikipedia.org/wiki/IEEE_802.11e-2005#Enhanced_distributed_channel_access_.28EDCA.29 In linux wifi at least: CS0, CS3 are mapped into the BE hw queue CS1, CS2 are mapped into the BK hw queue CS4, CS5 are mapped into the VI hw queue CS6, CS7 are mapped into the VO hw queue Bit patterns for the other classes to whatever extent they map into CSX are mapped into the underlying hardware queue. I am not saying this is an optimal state of affairs, (as notably VO should be as completely disabled as possible in the 802.11n and ac age), and am very interested in how other OSes (ios, osx, windows), and router/switch OSes do it, but the wireless scheduling aspect of all these codepoints does not seem to be well touched upon. On a personal note I tend to think that having 17+ ways to slice up traffic is about 13 or 14 too many, particularly those targetting a drop probability. When you have drop rates well below a few percentage points, adding another percentage point of granularity seems futile. Lastly, there is also an implementation issue in linux presently in that doing extensive diffserv classification basically requires one iptables or tc rule per class, which is inefficient. Someone (not me!) doing some code for doing diffserv saner there would go a long way... -- Dave Täht NSFW: https://w2.eff.org/Censorship/Internet_censorship_bills/russell_0296_indecent.article
- [Dart] WGLC: draft-ietf-dart-dscp-rtp-02 Ben Campbell
- Re: [Dart] WGLC: draft-ietf-dart-dscp-rtp-02 Ruediger.Geib
- Re: [Dart] WGLC: draft-ietf-dart-dscp-rtp-02 Black, David
- Re: [Dart] WGLC: draft-ietf-dart-dscp-rtp-02 Brian E Carpenter
- Re: [Dart] WGLC: draft-ietf-dart-dscp-rtp-02 Ruediger.Geib
- Re: [Dart] WGLC: draft-ietf-dart-dscp-rtp-02 Brian E Carpenter
- Re: [Dart] [rtcweb] Fwd: WGLC: draft-ietf-dart-ds… Dave Taht
- Re: [Dart] WGLC: draft-ietf-dart-dscp-rtp-02 Ruediger.Geib
- [Dart] WGLC: draft-ietf-dart-dscp-rtp-02 Gorry Fairhurst
- Re: [Dart] [rtcweb] Fwd: WGLC: draft-ietf-dart-ds… Brian E Carpenter
- Re: [Dart] WGLC: draft-ietf-dart-dscp-rtp-02 Ruediger.Geib
- Re: [Dart] WGLC: draft-ietf-dart-dscp-rtp-02 gorry
- Re: [Dart] WGLC: draft-ietf-dart-dscp-rtp-02 Brian E Carpenter
- Re: [Dart] WGLC: draft-ietf-dart-dscp-rtp-02 Ruediger.Geib
- Re: [Dart] [AVTCORE] WGLC: draft-ietf-dart-dscp-r… Colin Perkins
- Re: [Dart] [AVTCORE] WGLC: draft-ietf-dart-dscp-r… Ben Campbell
- Re: [Dart] [AVTCORE] WGLC: draft-ietf-dart-dscp-r… Black, David
- Re: [Dart] WGLC: draft-ietf-dart-dscp-rtp-02 Ben Campbell