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Poor communications

Poor communications have caused a lot of problems over the years. Fortunately for you I’m not a therapist and this isn’t a self-help column, so we’ll be limiting ourselves to communications of the kind that happen between computers. You think we humans have communications problems…

Let’s start with a simple history lesson on computer communications. The precursor of modern networks started with hubs, and a cable running to each computer. Network cabling contains the signal, and each computer acts like a radio station, and we call this Ethernet communications. Each computer listens at the cable, and if they hear nothing, they would try and broadcast their information for all the others to hear. The computer the broadcast was intended for receives the information. If two computers try and broadcast at the same time, the whole system resets and randomly restarts. A network cable contains 4 pairs of wires and only two pair are used. Theoretically, this could carry 10 million bits of data per second (mb/s), but with the system resetting so frequently on busy networks, it was more realistic to say it carried about 4 mb/s. If you had 10 pictures from a good digital camera, and were transferring them over the network, you could expect it to take about 80 seconds.

Hubs have been replaced with switches, which isolate traffic, allowing multiple computers to broadcast at the same time. Technology improvements allowed computers to send and receive at the same time, using the pairs of wires differently. Data speeds on most networks today are capable of 100mb/s, and in the last few years, most computers are capable of 1000mb/s or 1 billion bits of data per second. Those same 10 pictures can take 8 seconds, and less than a second, respectively. So, if things are so much faster, how come it doesn’t feel any faster?

Network cabling is not like running electrical wire. Just because you have a connection, doesn’t mean it’s going to work well. Imagine a lamp getting half or a third of the power, and burning dimly. Any computer you buy today should be capable of 1000mb/s or Gigabit Ethernet. Many offices have replaced their switches with new switches capable of supporting Gigabit speeds. Unfortunately, I would estimate that 80% of the cabling I see is poor. It might work, but you can’t expect that it will be fast just because it connects. Running at these high speeds is only possible when the cabling is excellent. The network drops down to lower speeds in order to communicate efficiently when conditions are poor. The process of negotiating or switching speeds also causes delays, causing further problems.

Common signs of problem cabling:

  • Metal staples securing cables - Staples cause problems and are not used by professional installers.
  • Cabling kinked or bent to sharp angles - Kinks and bends disrupt the twists in the cable causing interference.
  • Data cables alongside power or florescent lights - Cables can run across lights or power, but not parallel.
  • Cables have identification printed on them that say Cat 5 or Cat 4 - These are older cables and not designed to support higher transmission speeds. Ensure you have Cat 5e as a minimum.
  • Cable ends should terminate in a jack and should not have an end crimped on - Homemade cables are prone to failure and indicate a poor quality installation job. Patch cables between the jack and computer are very reliable and cheap.

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About the Author

Mark Smed started as a self-employed consultant, integrating computers into small business in 1989.  The range of work expanded into installing networks and consulting with businesses on the fast paced changes in technology.  As his career progressed he taught Network Administration at a small business college and continued to build his base of clients. 

Today, Mark works for Northern Computer Inc. (http://www.northerncomputer.ca) as a consultant, specialist and technician.  His client base continues to grow and many of his clients have worked with him for over 10 years now.  In 2001, Mark joined the Network Professional Association (http://www.npa.org) and now sits on the board of directors and is responsible for publishing the Network Professional Journal for the association.

Mark can be reached at [email protected].

The views expressed are strictly those of the author and not necessarily those of Castanet. Castanet does not warrant the contents.

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