Re: [aqm] Question re draft-baker-aqm-recommendations recomendation #4
Michael Welzl <michawe@ifi.uio.no> Mon, 06 May 2013 19:36 UTC
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From: Michael Welzl <michawe@ifi.uio.no>
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Date: Mon, 06 May 2013 21:36:15 +0200
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To: John Leslie <john@jlc.net>
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Cc: "Fred Baker (fred)" <fred@cisco.com>, aqm@ietf.org
Subject: Re: [aqm] Question re draft-baker-aqm-recommendations recomendation #4
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On May 6, 2013, at 9:17 PM, John Leslie <john@jlc.net> wrote: > Michael Welzl <michawe@ifi.uio.no> wrote: >> >> About this recommendation, I agree regarding what it actually >> recommends, but I have a comment about the wording. This bit: >> >> "Hence, Active Queue Management algorithms that are effective with >> all of those transports and the applications that use them are to be >> preferred." >> ... > > I think some wordsmithing would help... > ] > ] 4.4. Active Queue Management algorithms deployed SHOULD be effective on > ] all common Internet traffic > > At the outset, do we mean to say that AQM specifications SHOULD > have, e.g., a "UDP Considerations" section? (That's one way to read > this.) > > Or do we mean that AQM SHOULD NOT be optimized for TCP? > > Or do we mean there exist some magical principles which enable > AQM designers to optimize for IP traffic we haven't thought of yet? > > ] Active Queue Management algorithms often target TCP [RFC0793], as it > ] is by far the predominant transport in the Internet today. However, > ] we have significant use of UDP [RFC0768] in voice and video services, > ] and find utility in SCTP [RFC4960] and DCCP [RFC4340]. Hence, Active > ] Queue Management algorithms that are effective with all of those > ] transports and the applications that use them are to be preferred. > > I'm not the least bit sure that "target TCP" is the point. There's > an incredible range of traffic carried over TCP. It's typical for an > AQM proposal to be tested in terms of how a bulk-transfer TCP reacts > vs. an "interactive" web session series of "short" TCP streams. This, > IMHO, isn't "targetting" TCP, but rather comparing bulk transfer vs. > on-demand short-transfer -- where both happen to use TCP transport. > They could just as well be using SCTP or any of several other transports. > > Do we mean to say that things would be significantly better if the > tests were altered to use SCTP for some of the sessions? > > Besides, whether sessions are mixed transports or all TCP, the > congestion-control algorithms are in fact varied. Don't we mean to say > that AQM algorithms SHOULD work with a variety of congestion control > algorithms? > > If we do mean to require consideration of multiple _transports_, > what do we wish to see considered? I don't get much of a hint from > this text. > > Back to Michael: > >> sounds as if it would be the most normal thing in the world for an >> AQM algorithm to make a decision based on the transport protocol, >> which I think it shouldn't. > > That's certainly one "solution"... And I also dislike it. > >> To me, ECN is an IP-layer signal and routers shouldn't have to >> investigate what's layered on it (which may go beyond just looking >> at the "protocol" field in case of tunnels) in order to make their >> decisions. > > Yes, but... > > It seems unlikely that we're going to get a fully satisfactory AQM > without separate queues for different flows. I'd like to believe the > IPv6 flow label can give us what we need, but that's optimistic… Seems like a case of "more specific and more complicated" vs. "more vague but perhaps good enough" to me. I don't think that there's a reasonable way to be more specific here, but maybe I'm just missing it. Cheers, Michael >> I tried to come up with a better phrasing but failed... maybe it >> could be an idea to just add a sentence after this one, saying >> something like "Such algorithms do not need to consider any >> information in the packet beyond its IP header." > > I think more substantial rewording is needed. I'll be happy to > suggest wording _after_ I see a better understanding of what we mean > to say here. > > -- > John Leslie <john@jlc.net>
- [aqm] Question re draft-baker-aqm-recommendations… Fred Baker (fred)
- Re: [aqm] Question re draft-baker-aqm-recommendat… Michael Welzl
- Re: [aqm] Question re draft-baker-aqm-recommendat… Linda Dunbar
- Re: [aqm] Question re draft-baker-aqm-recommendat… Fred Baker (fred)
- Re: [aqm] Question re draft-baker-aqm-recommendat… John Leslie
- Re: [aqm] Question re draft-baker-aqm-recommendat… Michael Welzl
- Re: [aqm] Question re draft-baker-aqm-recommendat… John Leslie
- Re: [aqm] Question re draft-baker-aqm-recommendat… grenville armitage
- Re: [aqm] Question re draft-baker-aqm-recommendat… John Leslie
- Re: [aqm] Question re draft-baker-aqm-recommendat… grenville armitage
- Re: [aqm] Question re draft-baker-aqm-recommendat… Michael Welzl
- Re: [aqm] Question re draft-baker-aqm-recommendat… Fred Baker (fred)
- Re: [aqm] Question re draft-baker-aqm-recommendat… Bob Briscoe
- Re: [aqm] Question re draft-baker-aqm-recommendat… Rong Pan (ropan)
- Re: [aqm] Question re draft-baker-aqm-recommendat… Rong Pan (ropan)
- Re: [aqm] Question re draft-baker-aqm-recommendat… Scott Brim
- Re: [aqm] Question re draft-baker-aqm-recommendat… Bob Briscoe
- Re: [aqm] Question re draft-baker-aqm-recommendat… Bob Briscoe