Re: [rmcat] [tsvwg] FW: Fwd: Submitted ID on delay vs. loss-only rate-adaptive for DiffServ

[James Polk <[e-mail]>]

At 02:55 PM 7/17/2013, Brian E Carpenter wrote:
>On 17/07/2013 18:50, [e-mail] wrote:
> > I think the question of sharing diffserv is important, and my current
> > suggestion is that RMCAT should use one or at most two DSCPs and design a
> > CC that works well within the class - however this does not absolve RMCAT
> > from also having to work in the Internet without this class. This will
> > likely be the main use-case!
> >
> > Although the proposal could help these applications - the IETF can not
> > somehow mandate this is universally deployed - and even if the DSCP(s)
> > were universally recognised, it would still be aggregated within some
> > networks and on L2 technologies that support fewer classes than DSCP
> > markings.
> >
> > It would be interesting to know if others think we should be considering
> > more DSCPs for this?
>
>If you mean "more" in the sense of defining new PHBs, I sincerely hope
>not. Diffserv works best with a small set of highly differentiated
>PHBs. Also, in order to get cross-domain agreements on DSCP assignments,
>the fewer there are the better.

Brian - while I agree less is more manageable, but less what? Isn't 
'the less' or "... a small set..." you're referring to actually about 
treatment aggregates, defined by RFC 5127 (where similar PHBs are 
aggregated into 'treatment aggregates' to all be treated the same 
where we have big pipes)? Treatment Aggregates would see all of the 
above video traffic in the same individual treatment aggregate, 
solving the issue you bring up that _not_ any more treatment 
aggregates are defined.

James


>     Brian
>
> >
> > Gorry
> >
> >> I support something like what this draft proposes, to segregate RMCAT (and
> >> potentially other delay-adaptive traffic) from other traffic which does
> >> not adapt to delay trends (and therefore incurs maximum queue delay for
> >> all traffic in its queue). Of course, this only helps when such queue
> >> segregation is available in the network, but effective active queue
> >> management is not available (otherwise there would be no delay signals for
> >> delay-adaptive traffic to act on).
> >>
> >> An open question in my mind, that I think this draft needs to address, is
> >> whether all delay-adaptive traffic should share the same queue/DSCP, or
> >> whether we need different queues/DSCPs for different delay-adaptive
> >> protocols/applications (for example, RMCAT vs. LEDBAT).
> >>
> >> Mo
> >>
> >> -----Original Message-----
> >> From: [e-mail] [mailto:[e-mail]] On Behalf Of
> >> James Polk (jmpolk)
> >> Sent: Tuesday, July 16, 2013 5:11 PM
> >> To: Cheng-Jia Lai (chelai); James Polk (jmpolk); Toerless Eckert (eckert);
> >> Michael Ramalho (mramalho); [e-mail]; [e-mail]
> >> Subject: Re: [rmcat] [tsvwg] FW: Fwd: Submitted ID on delay vs. loss-only
> >> rate-adaptive for DiffServ
> >>
> >> CJ
> >>
> >> Thank you for the quick review.
> >>
> >> I'll ask you the same question I just asked Michael, the draft isn't
> >> very long (under 8 pages currently), and it is a work in progress -
> >> but do you have text or just points that this draft needs to cover
> >> that it doesn't currently?
> >>
> >> James
> >>
> >> At 01:36 PM 7/16/2013, Cheng-Jia Lai (chelai) wrote:
> >>> Same here... I feel it makes sense to create a new DSCP / CS4 for
> >>> transport of video flows that have rate adaptive behaviors and/or
> >>> intra-flow preferential drop priorities as indicated in the I-D. The
> >>> service provided by the network may thus be considered new, i.e.
> >>> different from what exists in AF4x, so IMHO, using a new or reusing
> >>> CS4 service class adds clarity for the user applications.
> >>>
> >>> Regards,
> >>> CJ
> >>>
> >>>
> >>> -----Original Message-----
> >>> From: [e-mail] [mailto:[e-mail]] On
> >>> Behalf Of Michael Ramalho (mramalho)
> >>> Sent: Tuesday, July 16, 2013 6:36 AM
> >>> To: [e-mail]
> >>> Subject: [tsvwg] FW: [rmcat] Fwd: Submitted ID on delay vs.
> >>> loss-only rate-adaptive for DiffServ
> >>>
> >>> TSVWG Members,
> >>>
> >>> I should have copied you on my email to the RMCAT mailer below.
> >>>
> >>> I strongly support the creation of a new DSCP for transports in
> >>> which their congestion control can adapt based on delay.
> >>>
> >>> The current ID in support of this
> >>> 
> (http://www.ietf.org/internet-drafts/draft-polk-tsvwg-delay-vs-loss-ds-service-classes-00.txt
> >>> ) is a work in progress, but a step in the right direction.
> >>>
> >>> It is a given that the ability of the eventual RMCAT adaptation
> >>> mechanisms to achieve low delay will be function of the other
> >>> dominant traffic it is competing against. If the dominant competing
> >>> traffic DEPENDS on loss, the RMCAT packets are held hostage to being
> >>> delayed by the bottleneck queue delay maximum.
> >>>
> >>> Thus, whenever possible, it will be preferable for RMCAT flows to
> >>> compete with other congestion control transports that adapt on
> >>> delay. Even this may not get us to the desired low-delay goals when
> >>> a portion of the traffic has long RTTs (i.e., adaptation control
> >>> loops that are long in time), or for links that have a highly-time
> >>> varying capacity,  but it will help for a lot of common bottleneck
> >>> topologies (e.g., slowly time-varying access bufferbloat).
> >>>
> >>> It is my hope that this topic has some discussion time in the Berlin
> >>> Transport WG (not the specific codepoint to be chosen, but rather
> >>> the need for one).
> >>>
> >>> Off Soapbox,
> >>>
> >>> Michael Ramalho, Ph.D.
> >>>
> >>> -----Original Message-----
> >>> From: Michael Ramalho (mramalho)
> >>> Sent: Tuesday, July 16, 2013 9:06 AM
> >>> To: [e-mail]
> >>> Subject: RE: [rmcat] Fwd: [tsvwg] Submitted ID on delay vs.
> >>> loss-only rate-adaptive for DiffServ
> >>>
> >>> RMCAT Design Team,
> >>>
> >>> The draft Lars references below is a formal request for a DSCP
> >>> dedicated to "RMCAT-only (or other nice delay-based cc) traffic".
> >>>
> >>> It will take a while to become socialized ... and we can progress
> >>> our RMCAT work in the interim.
> >>>
> >>> Michael Ramalho
> >>>
> >>> -----Original Message-----
> >>> From: [e-mail] [mailto:[e-mail]] On
> >>> Behalf Of Eggert, Lars
> >>> Sent: Tuesday, July 16, 2013 5:26 AM
> >>> To: WG WG
> >>> Cc: [e-mail]
> >>> Subject: [rmcat] Fwd: [tsvwg] Submitted ID on delay vs. loss-only
> >>> rate-adaptive for DiffServ
> >>>
> >>> Possibly of interest to RMCAT.
> >>>
> >>> Begin forwarded message:
> >>>
> >>>> From: James Polk <[e-mail]>
> >>>> Subject: [tsvwg] Submitted ID on delay vs. loss-only
> >>> rate-adaptive for DiffServ
> >>>> Date: July 16, 2013 8:07:59 GMT+02:00
> >>>> To: <[e-mail]>
> >>>>
> >>>> (as an author)
> >>>>
> >>>> Toerless and I put together a draft about legacy rate-adaptation
> >>> based only on loss vs. what RMCAT is looking to (for RTCWEB), which
> >>> is based on delay and loss.  Here's the URL.
> >>>>
> >>> 
> http://www.ietf.org/internet-drafts/draft-polk-tsvwg-delay-vs-loss-ds-service-classes-00.txt
> >>>> It's more raw than we had in mind, but we believe this is
> >>> necessary, based on implementation experience and what users and
> >>> customers have in their networks, or are planning on having in
> >>> their networks soon.
> >>>> James & Toerless
> >>>>
> >
> >
> >