[e2e] TCP un-friendly congestion control

[Richard Carlson]

Saverio;

In the I2-LSR awards listed below, no there isn't much *any* TCP could do 
to improve performance.  Both IPv4 and IPv6 results were limited by the e2e 
path capacity - 2.4 Gbps (OC-48) for the IPv4 record and 1 Gbps (GigE) for 
the IPv6 record.  Both records use over 95% of the path capacity.  These 
records show what TCP is capable of achieving.

In the general case, where a specific flow is competing with other flows, 
then any algorithm that can improve TCP's response time to loss events - 
congestion or BER - would improve throughput.  Exactly what these 
algorithms are is an active research area at the present time.  I, for one, 
would be very interested in TCPW experiments over long/fat networks.

Rich

At 09:03 PM 6/9/03 +0200, Saverio Mascolo wrote:
>Richard,
>
>do you think that e2e bandwidth estimation a la Westwood could improve TCP
>over high speed paths?
>
>At   http://www-ictserv.poliba.it/mascolo/tcp%20westwood/Results24.htm
>
>we report some tests obtained using an implementation of Westwood in Linux
>2.4. We have executed ftp  from Bari (South of Italy) to Uppsala, Sweden,
>and Ucla, California. Some interesting improvements have been found. A
>complete report along with the Linux code will be available soon.
>
>Saverio
>-----------
>Saverio Mascolo, Ph.D
>Associate Professor
>Dipartimento di Elettrotecnica ed Elettronica, Politecnico di Bari
>Via Orabona 4, 70125 Bari,  Italy
>email: mascolo at poliba.it
>http://www-dee.poliba.it/dee-web/Personale/mascolo.html
>
>
>----- Original Message -----
>From: "Richard Carlson" <RACarlson at anl.gov>
>To: <end2end-interest at postel.org>
>Sent: Monday, June 09, 2003 5:04 PM
>Subject: Re: [e2e] TCP un-friendly congestion control
>
>
> > As chair of the Internet 2 Land Speed Record judging committee, I can
> > confirm that TCP over long fat networks is not hopeless.  The last 2
> > records, using IPv4 and IPv6, show that hosts can push the network to the
> > limit.  For the latest IPv4 record a team from the US and Europe ran Iperf
> > for 3700 seconds (yes just over 1 hour) between 2 PC's with 10 Gigabit
> > Ethernet NICs.  They achieved a throughput rate of 2.3 Gbps, with the
> > connection being limited by a transatlantic OC-48 link.  The latest IPv6
> > record is being processed now, but it is equally impressive.  See the
> > I2-LSR web page http://lsr.internet2.net for details.
> >
> > Another thing to consider, Les Cottrell from SLAC ran some tests with
>these
> > 10 Gig NICs and tested the standard Linux 2.4 TCP, FAST TCP, HPTCP, and
>one
> > other high performance implementation.  These tests showed no difference
> > between any of the TCP implementations over 1 particular network path.  If
> > Les is on this list maybe he can provide a pointer to these results.
> >
> > Rich
> >
> > At 05:26 PM 6/6/03 -0400, Craig Partridge wrote:
> >
> > >In message <20030606140028.A59651 at xorpc.icir.org>, Luigi Rizzo writes:
> > >
> > > >exactly -- that's the whole point, the packet rate is so high that
> > > >there are many chances to have occasional losses anywhere in the
> > > >system, not just due to the channel but even because of operating
> > > >system issues on some of the intermediate boxes or end nodes.
> > >
> > >OK, let me get on my high horse here for a moment.
> > >
> > >The original poster asserted that in an environment where the network
> > >went at 1 Gbps and had 50ms of delay, TCP was hopeless.
> > >
> > >The point I was trying to drive home is that it is not hopeless.  That
> > >you have to define the environment far more carefully before you assert
> > >that TCP can or cannot do the job.  One of my frustrations these days is
> > >people who fail to be careful.  I was trying to encourage care in the
> > >problem statement.
> > >
> > >Thanks!
> > >
> > >Craig
> >
> > ------------------------------------
> >
> > Richard A. Carlson                              e-mail: RACarlson at anl.gov
> > Network Research Section                        phone:  (630) 252-7289
> > Argonne National Laboratory                     fax:    (630) 252-4021
> > 9700 Cass Ave. S.
> > Argonne,  IL 60439
> >

------------------------------------

Richard A. Carlson                              e-mail: RACarlson at anl.gov
Network Research Section                        phone:  (630) 252-7289
Argonne National Laboratory                     fax:    (630) 252-4021
9700 Cass Ave. S.
Argonne,  IL 60439