Re: [rtcweb] DSCP marking for STUN packets
Dave Taht <dave.taht@gmail.com> Wed, 12 March 2014 08:35 UTC
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Date: Wed, 12 Mar 2014 08:35:29 +0000
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From: Dave Taht <dave.taht@gmail.com>
To: Justin Uberti <juberti@google.com>
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Cc: Keith Winstein <keithw@mit.edu>, "rtcweb@ietf.org" <rtcweb@ietf.org>
Subject: Re: [rtcweb] DSCP marking for STUN packets
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On Wed, Mar 12, 2014 at 3:55 AM, Justin Uberti <juberti@google.com> wrote: > > > > On Tue, Mar 11, 2014 at 10:17 AM, Dave Taht <dave.taht@gmail.com> wrote: >> > >> > Whether that always translates to "the highest DSCP code point" is .... >> > a good question. >> >> It doesn't. Keith added af42 support to mosh last year and had several >> reports of packets being dropped with that marking. Worse the drops happened >> after 10 seconds of connectivity. >> >> Ecn markings on the other hand have thus far survived (if occasionally >> stomped on) across the open internet in that protocol. > > > This is a concern of mine as well, which is why we haven't yet flipped the > switch to turn DSCP on by default in Chrome. I think we'll need to do some > experimentation to see how often DSCP makes things worse. Well, while I'm at this, I note that how linux handles DSCP in WIFI 802.11e is generally suboptimal. the CS6 and CS7 bit patterns map to the VO queue which is not aggregatable in wireless-n, CS4 and CS5 map to the VI queue which has a lot of good properties for videoconference and voice traffic (but limited aggregation), and CS1 and CS2, which map to the background queue, which has good aggregation but limited txops. I no longer have the bit patterns for AFxx memorized, but basically all that was returned to the 802.11e classifier was dscp >> 5 up until very recently. Lastly, there really is no interpretation whatsoever of the AF classes equating to "drop probability" in wifi (at least in lnux), they merely control queue selection and it is generally better with wireless-n to aim for better aggregation in one queue rather than using multiple queues as the cost of acquiring the media dominates. -- Dave Täht Fixing bufferbloat with cerowrt: http://www.teklibre.com/cerowrt/subscribe.html
- [rtcweb] DSCP marking for STUN packets Muthu Arul Mozhi Perumal (mperumal)
- Re: [rtcweb] DSCP marking for STUN packets Justin Uberti
- Re: [rtcweb] DSCP marking for STUN packets Muthu Arul Mozhi Perumal (mperumal)
- Re: [rtcweb] DSCP marking for STUN packets Dave Taht
- Re: [rtcweb] DSCP marking for STUN packets Magnus Westerlund
- Re: [rtcweb] DSCP marking for STUN packets James Polk
- Re: [rtcweb] DSCP marking for STUN packets Simon Perreault
- Re: [rtcweb] DSCP marking for STUN packets Harald Alvestrand
- Re: [rtcweb] DSCP marking for STUN packets Dave Taht
- Re: [rtcweb] DSCP marking for STUN packets Justin Uberti
- Re: [rtcweb] DSCP marking for STUN packets Justin Uberti
- Re: [rtcweb] DSCP marking for STUN packets Magnus Westerlund
- Re: [rtcweb] DSCP marking for STUN packets Dave Taht
- Re: [rtcweb] DSCP marking for STUN packets Muthu Arul Mozhi Perumal (mperumal)
- Re: [rtcweb] DSCP marking for STUN packets Justin Uberti
- Re: [rtcweb] DSCP marking for STUN packets Magnus Westerlund
- Re: [rtcweb] DSCP marking for STUN packets Justin Uberti
- Re: [rtcweb] DSCP marking for STUN packets Harald Alvestrand
- Re: [rtcweb] DSCP marking for STUN packets Dave Taht