Web100 on Track

Web100 on Track

Researchers tune up software to boost bandwidth


The National Science Foundation has awarded a $2.9 million, three-year grant to the Web100 Project, which will attempt to fine-tune software to exploit 100 percent of available network bandwidth.

The project is a collaborative effort of the Pittsburgh Supercomputing Center, the National Center for Atmospheric Research and the National Center for Supercomputing Applications. They are tuning a freeware operating system, a Web server and a Web browser to give better end-to-end network performance.

More doesn't mean better

The roadblock to fast networking is not backbone bandwidth, project participants said. Allocating more and more bandwidth has not translated into end-to-end performance improvements.

Many government users have access to 100-Mbps networks, but in reality they seldom get even 10 Mbps on single-stream TCP transfers. The reason is that the Transmission Control Protocol is optimized for low-bandwidth environments.
Web100 hopes to make bandwidth-tweaking unnecessary with its improved software products.

'We've had the NSF money for only a couple of months, so we're just starting out,' said Matt Mathis, network research coordinator for the Pittsburgh Supercomputing Center.

The program so far has produced 'some very preliminary code' that has been distributed to a handful of people, Mathis said. 'This is really material for other developers, not users.'

But interest in Web100 already is 'autohyping,' he said.

Web100 developers work with existing software. They chose the Linux operating system, the Apache Web Server and AOL Communicator, formerly Netscape Navigator, because the source code is available, the programs are widely used, and there is a good chance the consortium can widely distribute enhanced versions.

Intel-based Linux will be the first development platform, although plans call for versions for the Compaq Alpha platform, Mathis said.

Initial work began on the Linux 2.2.14 kernel, but that has changed to the shared kernel, Version 2.2.16. The beauty of the open source code is that 'when you've skinned one cat, you've skinned them all,' Mathis said.

The first task is to improve the Linux TCP stack that supplies transport functions. It will 'automatically and transparently optimize the transmit and receive buffer sizes using network congestion feedback,' said Basil Irwin, senior network engineer at NCAR.

Plans also include creating a new management information base for TCP to replace the current TCP-MIB. The new one will be incorporated in the Linux kernel to do a better job of autotuning, locating bottlenecks and adjusting to network conditions.

Web100 plans to make the code downloadable from its Web site by the end of the first year, and to have a complete CD-ROM ready for distribution early the second year. Help desk services will be available to beta users in the second year.
By the third year, Web100 plans production versions of the full software package and hopes that commercial Linux distributors will adopt its kernel changes.

There could be bad side effects to fine-tuning the software for maximum network speed, Mathis warned. 'There are so few well-tuned clients and applications that it is often disruptive to other clients to have a well-tuned system on a network,' he said.

He likened it to keeping a minivan clear of a Formula 1 racing car on a highway with no speed limits. 'We want to avoid reducing networks to rubble by accident,' he said.

size="2" color="#FF0000">Many government users have 100-Mbps networks, but in reality they seldom get even 10 Mbps on single-stream TCP transfers.

The Defense Advanced Research Projects Agency is Web100's model for stimulating networking advances in commercial products. DARPA funded development of the socket functions in Unix source code that enabled TCP/IP networking. When demand for TCP/IP capability grew, vendors began incorporating the technology into commercial operating systems.

Web100 hopes to see its freeware adopted by academicians and researchers who are hungry for greater networking efficiency. That in turn could drive more demand and induce vendors to offer the improvements in their products.

The enhanced software would not increase bandwidth, only make better use of what is available. But the developers say they believe it will spur deployment of broadband connections to end users who want supercharged applications.

'Web100 could be a reason for making the investment necessary to bring megabit bandwidth to homes,' the project's concept paper said.

More information about Web100 is available at www.web100.org.


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