Re: [aqm] updated draft charter

[Bob Briscoe <[e-mail]>]

Dave,

One or two clarifications inline...

At 03:12 12/07/2013, Dave Taht wrote:
>On Thu, Jul 11, 2013 at 6:56 PM, Bob Briscoe <[e-mail]> wrote:
> > 5/ I suggest the enumerated bullets are changed to those below:
> >
> > "The Active Queue Management and Packet Scheduling working group
> >   works on algorithms for proactively managing queues in
> >   order to:
> >
> >   (1) Minimise standing queues
> >
> >   (2) help flow sources control their sending rates without unnecessary
> >   losses, e.g. through ECN
>
>I really remain dubious about usage of ECN on the world wide internet.
>If deployed widely, attacks will widely use it.
>
> >   (3) help minimize delays for interactive applications
> >
> >   (4) /consider the merits of various techniques/ to protect flows from
> > negative impacts of other more
> >   aggressive or misbehaving flows
> >
> > Reasoning:
> >
> > ECN: The original text was:
> > "(1) help flow sources control their sending rates before the
> >   onset of necessary losses, e.g. through ECN"
> > is not accepted wisdom. What's written in RFC3168 makes sense: that marking
> > for ECN traffic has to start at exactly the same point as loss for non-ECN
> > traffic. Otherwise ECN traffic starves itself. Certainly, under v 
> heavy load
> > everyone has to take losses, whether ECN or not, but I don't think that's
> > what you're talking about here.
> >
> > Protecting flows:
> > The question of whether/how to recommend flow isolation or not is part of
> > chartered work - the outcome shouldn't be prejudged in the charter.
>
>I'm a little vague on your intent here.

I've suggested adding the words "consider the merits of various 
techniques" in front of "protect flows from negative impacts of other 
more aggressive or misbehaving flows"

This is a minefield, so the charter has to tread carefully, that's all.

> > 7/ "  The working group will not make changes to ECN, DiffServ, or other
> >   IETF protocols, though existing ECN, DiffServ, and other mechanisms
> >   may be used within the algorithms proposed.
> > "
> > Add: The proper place for changes to ECN & Diffserv is TSVWG, but clearly
> > any such changes will need to be co-ordinated with the AQM WG, given the
> > code is likely to be entwined with AQM code.
>
>I'm not sure that this scope needs to be so limited here.

For ADs & chairs to discuss. I'm just trying to make the issue of WG 
demarcation explicit.

> > 9/ Gap in charter coverage?

[snip]

> > We have found that with multiple real-time video streams, they all have
> > highly variable rates, so they multiplex really well together in a FIFO.
> > However, if you put them through FQ or WRR, they all get forced into ruts
> > that are always the wrong size for all of them. This isn't a problem if the
> > sum is not often close to capacity (which is why SFQ can appear to be OK
> > with multiple videos). However, the whole point of isolation is to protect
> > flows when the system /is/ close to capacity.
>
>Cite? Not that I disagree, I've been ramping up at looking hard at
>webrtc behavior of late, just that most of my foci are focused on web,
>voip, and gaming traffic on the edge to date..

Citations below. However, none of these papers talks about the 
problems they encountered when trying to go live with the technology. 
They had to give up because WRR in production networks completely 
unwound the 205% multiplexing efficiency they achieved between video streams.

http://www.bobbriscoe.net/projects/refb/#Weighted_andor_Proportionally_Fair:
The three under Equitable quality streaming (it wasn't even real-time 
in their case):
    * Mulroy, P., Appleby, S., Nilsson, M. & Crabtree, B., 
"<http://research.microsoft.com/en-us/um/redmond/events/pv2009/papers/session_congestion_control/Paper%2018.pdf>The 
Use of MulTCP for the Delivery of Equitable Quality Video," In: 
Proc.<http://research.microsoft.com/en-us/um/redmond/events/pv2009/default.aspx> 
Int'l Packet Video Wkshp (PV'09) IEEE (May 2009)
    * Crabtree, B., Nilsson, M., Mulroy, P. & Appleby, S., 
"<http://research.microsoft.com/en-us/um/redmond/events/pv2009/papers/session_video/paper%204.pdf>Equitable 
quality video streaming over DSL," In: Proc. 
<http://research.microsoft.com/en-us/um/redmond/events/pv2009/default.aspx>Int'l 
Packet Video Wkshp (PV'09) IEEE (May 2009)
    * Nilsson, M., Crabtree, B., Mulroy, P. & Appleby, S., "Equitable 
quality video streaming for IP networks," International Journal of 
Internet Protocol Technology 4(1):65--76 (March 2009) DOI: 
10.1504/IJIPT.2009.024171

Bob



________________________________________________________________
Bob Briscoe,                                                  BT