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Network problem resolution areas often overlooked.

I have listened carefully to many

< users describe the design of their network,

the type of equipment and the test procedures for operating it, during the regional meetings the Association of Data Communications Users has sponsored around the country the past several months. They point with pride to all these factors < but then, almost as an aside, many of them admit they frequently have problems for which they cannot pinpoint responsibility. I listened to one manager describe his

< extensive, and usually reliable, network while his hip-pocket beeper went off three times in 90 minutes, signaling network problems "back at the shop." In networks as complex as most data

< communications managers operate today, that is not surprising. Therefore, it was interesting to spend time talking to Ed Hodgson, manager, computers and communications, Schindler Elevator Corporation, in New Jersey, who has identified some additional areas to investigate when other test procedures have not corrected troublesome malfunctions. I asked Hodgson where one should

< look if they are experiencing strange or ongoing, probably intermittent, errors or downtime problems in a normally reliable LAN, WAN, leased line or similar network configuration. He replied, "First of all, be certain

< you have eliminated power problems like noise and harmonic distortion, using isolated grounds and similar techniques. Then be certain you have grounded all cabling according to the NEC (National Electrical Code). "If this doesn't solve the problem, what < do you do next?" I asked Hodgson. And before he answered, I added, "Can you put it in outline form, sort of a checklist, that others could follow and not overlook any possibilities?" Hodgson complied with an outline

< identifying five areas where procedures and equipment should be checked. They are as follows: Have you installed a T1 for analog

< access to your modems? Then check the output levels from the T1 mux to the modems. Most modems will not operate correctly if the signal is greater than -20db to -30db. There are many multi-meters on the market that take db measurements. Ground your equipment and patch

< panel cabinets per the NEC. If these are not grounded, they are probably acting just like an ungrounded cable shield--a very good antenna and coupling device for signals. Check static electricity. An ungrounded

< anti-static carpet is worse than no carpet at all. Carpeting using plastic filaments for

< static conduction and anti-static sprays depends on some moisture being present--usually 40% humidity and above. With less than 40% humidity most of these products won't work at all--just when you need them. Using a private T1 (DS1)? Most carriers

< do not supply clocking, and the Stratum-3 or Stratum-4 clock in your mux is really not that good. It is time to look into a Stratum-1 or Stratum-2 clock. (Stratum is a CCITT standard.) Be sure that all of your equipment is

< set up for the correct clocking source: local, remote, slaved, master, internal, external, etc. Hodgson continued with these words

< of advice. "All of these conditions can, and will, cause problems that are difficult to isolate. Do a thorough job of determining the facts before starting. A 'let's try this and see if it works' attitude is usually counterproductive, especially if more than one of these causes are present at the same time." Those are profound words. I have listened

< to many network users complain bitterly about a network with frequent glitches that could have been "cleaned up" but was allowed to operate below design parameters. Those networks remind me of the computer

< programs that were turned loose years ago with sloppy documentation or no documentation at all and changes were almost impossible. "Getting the bugs out" applies equally to communications networks and computer programming--frequently one and the same. ADCU is fortunate to have members

< like Hodgson. He realizes network reliability is the most important factor to his company's users. Although Hodgson did not mention it,


I wondered, after my conversation with him, how companies can justify out-sourcing their most vital corporate responsibility, their communications network? Do they really believe a third party will zealously strive to get all the bugs out? Do they really believe they can ever rebuild a network and a department once it is disassembled?

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Title Annotation:Datacomm User
Author:Blegen, August
Publication:Communications News
Article Type:Column
Date:May 1, 1992
Previous Article:The race is on for leadership in network management.
Next Article:The crux of ISDN: what it does for your business.

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