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Mailbag: The minimum cable needed

Feb 11, 20033 mins

* Readers write in about what category of cabling is needed

Last month, I wrote a little bit about copper cabling, what would prompt an upgrade, and the early efforts of the IEEE to define a standard for 10 Gigabit Ethernet over copper cables. The articles generated quite a response, and I wanted to share some of those responses with you.

One reader says that Category 5 cabling, even for Gigabit Ethernet, is risky:

“You may have heard of people or organizations that have had to carry out desperate or ‘Hero’ efforts that used Cat 5 as the cabling medium, and maybe it did work. However, for you to say, ‘I have heard that plain old Cat 5 may work just as well,’ is just creating the impression in uneducated minds that they won’t need to budget or plan for new cabling in the future and this could lead to tragic and costly mistakes. If you were to state that ‘the IEEE has recommended that all new installations be built using Category 5E or better cabling’ and that ‘existing installations should be re-tested (using the new Cat 5E test suite) to verify that they are suitable for new Gigabit Ethernet applications,’ then your audience will be at least aware of the risks in using Category 5.”

That’s a good point. I think the thing to be aware of is that, as they say, individual results may vary. When I said I had heard that plain old Cat 5 could work, that was something mentioned by Network World columnist and tester Kevin Tolly a few months ago. He wrote, “To our surprise, some experiments run on subpar cabling would appear to support Dell’s assertion” that Cat 5 cabling would work:

In fact, Tolly mentioned to Network World editors that his testing group found the most beat-up, neglected and abused Cat 5 cable it could find, and it still ran Gigabit Ethernet. However, you may find your own environment needs something better.

Moving to 10 Gigabit, the question remains: What is the lowest class of cabling you can get away with? I heard from Ahmet Tuncay, the executive vice president of market development at SolarFlare Communications, a start-up specializing in copper 10 Gig:

“Your two recent articles on 10GBASE-T cabling were well done… At the IEEE meeting, installed base cabling issues have fostered significant discussion. As you noted, Bruce Tolley is promoting support for Cat 5 and end users are backing that view as well. Alan Flatman’s presentation was especially enlightening in this regard as it forecasts continued market share growth for Cat 5e through 2005 but erosion of the installed base of Cat 5. Most importantly, solutions are being presented here that will run on legacy cabling.”

Bruce Tolley also responded, providing this helpful link for more information:

“Thanks for the coverage of the 10GBASE-T study group. Various presentations by Mike Bennett and me were updated at the meeting and are now posted on the IEEE Web site. At some point over the next year we will have to decide which copper cabling types will be supported.”

Next time: What readers had to say about higher grades of cable.