Triad unravels 10Base-T twist-ups - Triad Systems Corp

Communications News, May, 1993 by Kip Meacham

Howard Gibbs, senior engineering technician at Triad Systems Corp. discovered that network cable diagnostic equipment can take the "twists" out of elusive twisted-pair wiring problems.

Triad, providers of business and information management solutions for the retail hardgoods and automotive aftermarkets, operates a PC network spanning three buildings and serving almost 700 employees at their world headquarters in Livermore, Calif.

In 1987-88, Triad installed ordinary telephone twisted-pair wiring (commonly called Level 3 wiring) for data stations used at the company. Level 3 cabling was "acceptable at the time for low level communications," says Gibbs. While overseeing the 10Base-T cabling of a major LAN downsizing project last fall, Gibbs found that certain workstations connected to the LAN properly, while others connected intermittently, or not at all.

Further investigation pointed Gibbs toward problems with the existing cabling, and Triad decided to purchase cable test equipment to uncover details of the cabling problem.

"As we are making the commitment to LANs, we determined it would be better to purchase the equipment because we would have it for future use," Gibbs comments.

Cabling problems were confirmed when Gibbs used a product from Microtest, Inc. called the MT310 Scanner. It is a hand-held cable diagnostic device designed for users of varying levels of technical expertise. It performs automatic testing and certification of twisted-pair network cabling.

Gibbs first used the MT310 and checked a cable run that was working correctly. He then contrasted those findings with a cable run that was working unreliably. He discovered the cabling runs over 160 feet in length that had reliably worked at the slower transmission speeds of their older system (6 Mb/s) would not perform reliably when operating at 10Base-T's higher speeds (10 Mb/s).

In measuring the cabling characteristics (including attenuation, NEXT, and crosstalk), Gibbs found the problematic cable runs violated specs for reliable 10Base-T operation.

Triad also had a few cable runs where no connection could be established, as they had completely failed to operate. Gibbs was able to isolate the location of shorts in these non-operational cable runs. In all cases, the tester confirmed and identified cabling problems that Gibbs could then remedy.

Since the isolation of the cabling problems, Triad has made several changes to their cabling, including installing the highest quality twisted-pair wiring available (commonly called Level 5 wiring).

Once new runs were installed, Gibbs used his MT310 to verify them. The Level 5 cabling runs met or exceeded requirements for reliable 10Base-T network operation.

"Buying this equipment really educated me. It has been very helpful in making sure connections to a central hub work," Gibbs says. He found that even the more technical aspects of cabling were understandable.

"I was mainly interested in setting the correct cable speed. I found that cable manufacturers do not reveal the velocity factors in their cable specifications. If they don't list it and you can't contact the vendor to figure this out, the manual tells how to use the scanner to determine this. I learned quite a bit about cables by having the scanner and learning by doing."

Gibbs shared his knowledge with several colleagues at Triad. He lends the equipment to other departments and instructs them its use. Other departments even used the Scanner to measure the length of test cables without stretching them out and measuring them.

"The cable radar works very well," Gibbs says.

As a result of this learning process, Triad now buys top quality, Level 5 twisted-pair wiring to preserve the company's investment in network cabling.

"When we cabled in 1987 with Level 3 cabling, we didn't think about the possibility that five years down the road, new network technologies would come at us. Using better cabling and testing will help us avoid problems next time," Gibbs concludes.