Re: [tcpm] TCP tuning
Murali Bashyam <MBashyam@OcarinaNetworks.com> Wed, 03 February 2010 22:01 UTC
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From: Murali Bashyam <MBashyam@OcarinaNetworks.com>
To: Jerry Chu <hkchu@google.com>, Joe Touch <touch@isi.edu>
Date: Wed, 03 Feb 2010 14:03:36 -0800
Thread-Topic: [tcpm] TCP tuning
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Cc: "tcpm@ietf.org" <tcpm@ietf.org>, "SCHARF, Michael" <Michael.Scharf@alcatel-lucent.com>
Subject: Re: [tcpm] TCP tuning
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Any idle period higher than the RTT between HTTP requests tends to reset the cwindow down to the restart window. This hurts persistent connections too. What's the motivation for this, can we have a different slope while reducing the window instead of resetting all the way down? -----Original Message----- From: tcpm-bounces@ietf.org [mailto:tcpm-bounces@ietf.org] On Behalf Of Jerry Chu Sent: Wednesday, February 03, 2010 1:39 PM To: Joe Touch Cc: tcpm@ietf.org; SCHARF, Michael Subject: Re: [tcpm] TCP tuning On Wed, Feb 3, 2010 at 11:26 AM, Joe Touch <touch@isi.edu> wrote: > > > Jerry Chu wrote: >> On Wed, Feb 3, 2010 at 7:17 AM, SCHARF, Michael >> <Michael.Scharf@alcatel-lucent.com> wrote: >>>> This topic seems to be gaining momentum, and the WG should >>>> take some time considering if there is work here for it. >>> IMHO there could indeed be room for increasing the initial window. If >>> most data transfers continue to be smaller than 3 MSS, a larger initial >>> window would not necessarily cause harm, as it is seldomly used. Still, >>> this would speed up those data transfers that currently suffer from >>> Slow-Start. >> >> Actually our data points to the contrary - the average web object and page >> size have been rising steadily. E.g., the majority of our search responses >> no longer fit in 3 MSS these days. > > This should be relevant only for the first response from a given IP > address; persistent connections should render this moot for subsequent > requests. Yes we are well aware of the advantage of maintaining persistent connections. In fact this is one of the reasons holding us back from resurrecting T/TCP (in addition to other security issues). But from our own observation the average HTTP connections just don't persistent that long for some reason. I don't remember the data or all the technical reasons on top of my head, but can surely try to get them for you. There are other limitations of HTTP 1/1: 1. obviously its effectiveness depends on user's web surfing pattern. 2. web browsers have been going down the slope of opening more and more simultaneous connections anyway, partly to circumvent HTTP's serialization, an issue SPDY tries to address. 3. practically web servers have only limited resources. can't hold too many open connections. 4. a web object will make the TCP slow start algorithm to grow its cwnd only upto the size of the object. As such, even with persistent connections, a web object that is larger than any of its predecessors will hit the window limit, and take more than one round trip time to complete. So persistent connections might not be as effective as one might think. > > Again, the question arises as to how much this is going to achieve a > noticeable impact. Quite significant in our study. Will present our result at IETF/Anaheim. Jerry > > Joe > > _______________________________________________ tcpm mailing list tcpm@ietf.org https://www.ietf.org/mailman/listinfo/tcpm
- [tcpm] TCP tuning Lars Eggert
- Re: [tcpm] TCP tuning Adam Langley
- Re: [tcpm] TCP tuning Michael Welzl
- Re: [tcpm] TCP tuning SCHARF, Michael
- Re: [tcpm] TCP tuning Stefanos Harhalakis
- Re: [tcpm] TCP tuning Kacheong Poon
- Re: [tcpm] TCP tuning Joe Touch
- Re: [tcpm] TCP tuning Kacheong Poon
- Re: [tcpm] TCP tuning Joe Touch
- Re: [tcpm] TCP tuning Michael Welzl
- Re: [tcpm] TCP tuning Joe Touch
- Re: [tcpm] TCP tuning Michael Welzl
- Re: [tcpm] TCP tuning Joe Touch
- Re: [tcpm] TCP tuning Adam Langley
- Re: [tcpm] TCP tuning Joe Touch
- Re: [tcpm] TCP tuning Jerry Chu
- Re: [tcpm] TCP tuning Michael Welzl
- Re: [tcpm] TCP tuning Michael Welzl
- Re: [tcpm] TCP tuning Joe Touch
- Re: [tcpm] TCP tuning Jerry Chu
- Re: [tcpm] TCP tuning Jerry Chu
- Re: [tcpm] TCP tuning Joe Touch
- Re: [tcpm] TCP tuning Jerry Chu
- Re: [tcpm] TCP tuning John Heffner
- Re: [tcpm] TCP tuning Jerry Chu
- Re: [tcpm] TCP tuning Jerry Chu
- Re: [tcpm] TCP tuning Biswas, Anumita
- Re: [tcpm] TCP tuning Jerry Chu
- Re: [tcpm] TCP tuning John Heffner
- Re: [tcpm] TCP tuning Jerry Chu
- Re: [tcpm] TCP tuning Biswas, Anumita
- Re: [tcpm] TCP tuning Michael Welzl
- Re: [tcpm] TCP tuning Jerry Chu
- Re: [tcpm] TCP tuning Murali Bashyam
- Re: [tcpm] TCP tuning Michael Welzl
- Re: [tcpm] TCP tuning John Heffner
- Re: [tcpm] TCP tuning Joe Touch
- Re: [tcpm] TCP tuning Joe Touch
- Re: [tcpm] TCP tuning Joe Touch
- Re: [tcpm] TCP tuning Joe Touch
- Re: [tcpm] TCP tuning Joe Touch
- Re: [tcpm] TCP tuning Jerry Chu
- Re: [tcpm] TCP tuning Marco Mellia
- Re: [tcpm] TCP tuning Joe Touch
- Re: [tcpm] TCP tuning Joe Touch
- Re: [tcpm] TCP tuning Jerry Chu
- Re: [tcpm] TCP tuning Joe Touch
- Re: [tcpm] TCP tuning Jerry Chu
- Re: [tcpm] TCP tuning rick jones
- Re: [tcpm] TCP tuning Joe Touch
- Re: [tcpm] TCP tuning Mike Belshe
- Re: [tcpm] TCP tuning rick jones
- Re: [tcpm] TCP tuning rick jones
- Re: [tcpm] TCP tuning Joe Touch
- Re: [tcpm] TCP tuning Alexander Zimmermann
- Re: [tcpm] TCP tuning Kacheong Poon
- Re: [tcpm] TCP tuning Kacheong Poon
- Re: [tcpm] TCP tuning SCHARF, Michael
- Re: [tcpm] TCP tuning SCHARF, Michael
- Re: [tcpm] TCP tuning Andrew Yourtchenko
- Re: [tcpm] TCP tuning Joe Touch
- Re: [tcpm] TCP tuning Jerry Chu
- Re: [tcpm] TCP tuning rick jones
- Re: [tcpm] TCP tuning Kacheong Poon
- Re: [tcpm] TCP tuning Joe Touch
- Re: [tcpm] TCP tuning SCHARF, Michael
- Re: [tcpm] TCP tuning rick jones
- Re: [tcpm] TCP tuning Joe Touch
- Re: [tcpm] TCP tuning Joe Touch
- Re: [tcpm] TCP tuning Jerry Chu
- Re: [tcpm] TCP tuning Joe Touch
- Re: [tcpm] TCP tuning Mike Belshe
- Re: [tcpm] TCP tuning Joe Touch
- Re: [tcpm] TCP tuning Mark Allman
- Re: [tcpm] TCP tuning Mark Allman
- Re: [tcpm] TCP tuning Mark Allman
- Re: [tcpm] TCP tuning Mark Allman
- Re: [tcpm] TCP tuning Mark Allman
- Re: [tcpm] TCP tuning Joe Touch