Thanks for posting your measurements on the web Injong.
Without getting into the merits or otherwise of the coefficient of
variation as a measure of anything users might care about, the
individual time history plots of throughput and cwnd look interesting.
I wonder if I could flag up some curious behaviour that seems evident in
the measurements for the cubic algorithm. In very many of the
individual time history plots it looks as if there are sustained periods
(extending to 100s of seconds) of substantial unfairness between
competing cubic flows with the same round-trip time. See for example:
http://netsrv.csc.ncsu.edu/highspeed/convex-ordering/FullSet_old/RTTFAIR/1MB_4HS_0FLF_2RLF_SLF_320MS/600--CUBIC-CUBIC-SIMPLE--400-3-667--1000-155-0-0-1-1-5-500--200000-0.6-1000-10-600-64000-150--24/
http://netsrv.csc.ncsu.edu/highspeed/convex-ordering/FullSet_old/RTTFAIR/1MB_4HS_0FLF_2RLF_SLF_320MS/600--CUBIC-CUBIC-SIMPLE--400-3-667--1000-155-0-0-1-1-5-500--200000-0.6-1000-10-600-64000-150--17/
Can you comment on this behaviour ? Perhaps I am misinterpreting the data.
I think its probably worth pointing out that in all the tests it looks
as if the cubic flows are all started at much the same time - is this
correct ? If so, the tests do not really probe the responsiveness of
cubic and it might well be useful to perform tests where the flows have
significantly different start times - it was this sort of experiment (by
ourselves a couple of years ago now - blowing my own trumpet, I know,
but what the heck :-)) that initially highlighted the convergence issues
with scalable-tcp, and the slow convergence of high-speed tcp and
bic-tcp. Slow convergence translates into possible sustained
unfairness, for example, against new flows starting up.
Doug
Hamilton Institute
www.hamilton.ie
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Today's Topics:
1. Stability of various TCP protocols [CUBIC, BIC, HTCP, HSTCP,
STCP] (Injong Rhee)
2. Re: performance of BIC-TCP, High-Speed-TCP, H-TCP etc
(Injong Rhee)
----------------------------------------------------------------------
Message: 1
Date: Thu, 28 Sep 2006 12:58:02 -0400
From: "Injong Rhee" <[EMAIL PROTECTED]>
Subject: [e2e] Stability of various TCP protocols [CUBIC, BIC, HTCP,
HSTCP, STCP]
To: <[EMAIL PROTECTED]>
Cc: netdev@vger.kernel.org
Message-ID: <[EMAIL PROTECTED]>
Content-Type: text/plain; charset="ks_c_5601-1987"
Hi,
I'd like to report on a measurement study regarding the stability of various TCP variant protocols. Although we can find quite a bit of work on fairness and convergence of protocols (including some theoretical studies on the topic as well), there is relatively little work on measuring the stability of protocols and its impact on protocol performance and overall health of the networks (e.g., the overall queue fluctions and link utilization). We have measured the degree of rate oscillation and fluctuation of protocols to have some understanding of protocol stability.
We would like to share our results with you to get some feedback from the community.
We have some theoretical results and also experimental results. Here is the
link to the experimental results. You can find links to all of our experimental
data that include results from several hundred experiments.
http://netsrv.csc.ncsu.edu/convex-ordering/
If you need our report on theoretical results, we can e-mail you the report.
Injong Rhee
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Message: 2
Date: Thu, 28 Sep 2006 12:33:32 -0400
From: "Injong Rhee" <[EMAIL PROTECTED]>
Subject: Re: [e2e] performance of BIC-TCP, High-Speed-TCP, H-TCP etc
To: <[EMAIL PROTECTED]>, <[EMAIL PROTECTED]>
Cc: netdev@vger.kernel.org, Douglas Leith <[EMAIL PROTECTED]>,
[EMAIL PROTECTED], [EMAIL PROTECTED],
[EMAIL PROTECTED]
Message-ID: <[EMAIL PROTECTED]>
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reply-type=response
Sure. I don't mind doing this test. I am currently working with Doug Leith
to get to the bottom of this difference. So when we get to the PFLDnet, we
should have some more findings on this. But I am up for this challenge.
----- Original Message -----
From: "Lachlan Andrew" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Cc: "Douglas Leith" <[EMAIL PROTECTED]>; <netdev@vger.kernel.org>;
<[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>; "Injong Rhee"
<[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>
Sent: Wednesday, September 27, 2006 7:20 PM
Subject: Re: [e2e] performance of BIC-TCP, High-Speed-TCP, H-TCP etc
Greetings all,
On 23/09/06, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
Just i was pondering why we got different results and try to see if we
can
come to some understanding on this different results we got. Who knows we
together might run into some fundamental research issues regarding
testing.
Since many interested parties will be around LA for PFLDnet, how about
getting together after that (Friday 9 Feb) to re-run some of the
disputed tests on one set of hardware, with everyone present to debate
the results?
You're all welcome to come to Caltech to do the testing. We can
provide a few servers, dummynets and Gigabit switches. Everyone is
welcome to bring their scripts, and any other hardware they need.
If there is interest, we could also have things like a round-table
discussion of the benefits of testing with different file-length
distributions (like long lived flows to understand what is happening
vs a range of flows to test suitability for deployment), and the
benefits of repeating other people's tests vs testing in as many
scenarios as possible.
Who is interested in coming?
Cheers,
Lachlan
--
Lachlan Andrew Dept of Computer Science, Caltech
1200 E California Blvd, Mail Code 256-80, Pasadena CA 91125, USA
Phone: +1 (626) 395-8820 Fax: +1 (626) 568-3603
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