Gigabit Ethernet probes tell all

SANTA CLARA -- Network Associates this week will catch up with today's fastest LANs, as the company for the first time releases a probe designed to collect data from Gigabit Ethernet lines.

Despite Gigabit Ethernet's increasing popularity, tools for measuring performance and diagnosing problems on the technology have lagged.

However, start-up Antara in the spring said it would feed data from its Gigabit Ethernet probe to Compuware's management software (Network World, April 26, page 7).

With the Network Associates approach, users attach the Distributed Sniffer System/ Remote Monitoring probe to a Gigabit Ethernet backbone in a remote location, and the probe sends the collected data back to a central site for troubleshooting.

Keeping an eye out

Law firm Arter & Hadden is planning to use the new Network Associates probe to keep an eye on LAN backbones in its offices around the country, says network engineer Vlad Agranovich. The firm, located in Cleveland, is in the process of installing Gigabit Ethernet switches in remote locations.

"The biggest problem we have is not having staff in all of our locations," Agranovich says. Even though he considers Gigabit Ethernet to be stable, he adds: "We don't want to get to the point where we're not watching the network."

High-speed probes have to be built somewhat differently than low-speed versions, says Paul Farr, vice president of network management at Network Associates.

One area of difference is filters. The Gigabit Ethernet probe does all its packet filtering in hardware, rather than software, to keep up with the high transmission speeds. This way, the probe can pick out packets belonging to a particular protocol or source, for example.

Different design

According to Farr, Gigabit Ethernet is also different than other Ethernet technologies in that it uses a 10-bit, rather than eight-bit, encoding scheme for characters. Command and control functions are encoded in the ninth and tenth bits, and the probe is designed to pick those up.

Because the bits govern autonegotiation of line rates, looking at them would give insight into why a connection might be running at 100M bit/sec instead of a full gigabit per second, Farr says.

Captured packets are stored in the probe's 144M-byte buffer and can be sent to a central location. At that location, the data can be sent to a reporting tool, such as Concord's Network Health or Network Associates' Informant software. Network Associates has similar probes for 10/100M bit/sec Ethernet, token-ring and ATM OC-3 networks.

The probe is available for two kinds of fiber Gigabit Ethernet. The 1000Base-SX version costs about $28,000, and the 1000Base-LX version costs about $30,000.

This story, "Gigabit Ethernet probes tell all" was originally published by Network World.

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