[FUGSPBR] OFF - Packet tracking promises ultrafast internet

[Marcus Voloch]

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http://www.newscientist.com/news/news.jsp?id=ns99993799

19:00 04 June 03

Special Report from New Scientist Print Edition

Imagine an internet connection so fast it will let you download a whole
movie in just five seconds, or access TV-quality video servers in real time.
That is the promise from a team at the California Institute of Technology in
Pasadena, who have developed a system called Fast TCP.
A key feature of Fast TCP is that it could run on the same internet
infrastructure we have today. Steven Low, who led the Caltech team, likens
the way the internet works now to driving a car while looking only 10 metres
ahead. You slowly increase the car's speed until an obstacle comes into
view, but then you have to hit the brakes.
"This is OK for driving slowly in a parking lot," says Low. But on the open
road you need to be able to look further ahead: "That's what we are doing
with Fast TCP."

.
Today, all traffic on the internet uses a system called the Transmission
Control Protocol (TCP) developed in the 1970s by network engineers Vinton
Cerf at Stanford University and Bob Kahn at the Pentagon's Defense Advanced
Research Projects Agency.

Safe arrival

TCP breaks down large files into small packets of about 1500 bytes, each
carrying the address of the sender and the recipient. The sending computer
transmits a packet, waits for a signal from the recipient that acknowledges
its safe arrival, and then sends the next packet.
If no receipt comes back, the sender transmits the same packet at half the
speed of the previous one, and repeats the process, getting slower each
time, until it succeeds.
This means that even minor glitches on the line can make a connection very
sluggish. Because Fast TCP uses the same packet sizes as regular TCP, the
hardware that carries messages around the net will still work. The
difference is in software and hardware on the sending computer, which
continually measures the time it takes for sent packets to arrive, and how
long acknowledgements take to come back.
This reveals the delays on the line, giving early warnings of likely packet
losses. The Fast TCP software uses this to predict the highest data rate the
connection can support without losing data.

Gigabits per second

Since the packets are the same size as those used in TCP, none of the
equipment along the internet itself will have to be modified, and no new
hardware will be needed on computers receiving the data.

The first practical test of Fast TCP took place in November at a
supercomputing conference. Researchers from Caltech, Stanford and CERN near
Geneva in Switzerland, sent data 10,000 kilometres from Sunnyvale,
California, to CERN at an average rate of 925 megabits per second. Ordinary
TCP managed just 266 megabits per second on the same routes.
By ganging 10 Fast TCP systems together, the researchers have achieved
transmission speeds of over 8.6 gigabits per second, which is more than 6000
times the capacity of ordinary broadband links.
The improved "Internet 2" infrastructure, currently being developed for
scientific data transmission between 200 universities around the world, will
use conventional TCP to run at around 350 megabits per second, but will run
even faster with Caltech's technology.
And the bandwidth-hungry entertainment industry is also looking at Fast TCP.
Caltech is already in talks with Microsoft and Disney about using it for
video on demand.

Barry Fox

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