Hidden Cable Flaws Slow Down Networks
Skokie, IL. When is Category 5 cabling not really
Category 5? Very often, according to cable giant Anixter,
Inc.
Network managers often confuse "uptime" with network
efficiency, according to Anixter cable engineer Tom Moxey.
While uptime is important, efficiency is a measure of how
fast data is actually moving through the network. Anixter
even coined and trademarked a word, "slowtime,"
to represent a state that isn't downtime but during which
the network is moving data more slowly than it should. Slowtime
conditions impact business costs, says Moxey, by reducing
worker productivity. Anixter cites a study by LeCroy
that found that annual productivity losses from reduced network
efficiency were more than twice losses from actual downtime.
Multiple factors cause slowtime, including environmental
conditions, poor quality network hardware, and even bandwidth-hogging
users. Many slowtime producers, though, are in an area that
many network experts give little thought to: the cabling and
cable components. These include problems like home-made patch
cords, improper cable stripping, too-tight cable bundling,
and the electrical properties of the cable itself.
Why do network managers ignore cable issues? Anixter, never
at a loss for words, has coined a phrase for that, too - the
"Green Light Fallacy." Simply put, hubs and network
cards usually have a green light indicating that data can
flow - when this light is on, everything is assumed to be
working at peak efficiency. In fact, when networks ran primarily
at 10 Mbps, this was usually the case. At that speed, cable
issues rarely impacted network performance unless connectivity
was completely lost.
Today, though, many businesses are running at least a portion
of their network at 100 Mbps, or so they think. In fact, actual
testing of 100 Mbps and 1000 Mbps networks show that more
often than not, they are operating at a fraction of their
rated speed. A 100 Mbps network, for example, might be performing
at a level of 60, 40, or even 20 Mbps. When users complain
that the network doesn't seem much faster than it used to
be, they may be accurate. Today's increased average file size
combined with much heavier use of the Internet and other wide
area links places much greater demands on the network; when
the network is operating at less than peak efficiency, users
notice the difference..
Anixter has set up its own laboratory to test cabling and
components in real-world environments. The Anixter Levels
Lab attempts to go beyond standard specifications and test
actual performance. This has enabled Anixter to label some
cables with their own performance ratings, and also to identify
ways to improve performance.
Do-It-Yourself Patch Cords?
According to Moxey, the lowly and often ignored patch cord
(the cable between the computer and the wall outlet) gets
far less attention than it deserves. Home-made patch cords
almost never work at full potential due to imperfect termination
- even when skilled cablers use proper tools. In addition,
matching the patch cord characteristics to the in-wall wiring
will maximize throughput. Of course, the in-wall wiring is
critical, too. One study by Anixter shows that for under $10
per drop per year, an organization could install "XP
7" cabling capable of 1000 Mbps instead of typical Cat
5e cable that won't allow speeds much faster than 10 Mbps.
 Len
Jablonski, Cabling Division Manager at Direct
Line Communications, echoes Moxey's sentiments.
"Clients don't realize that it's the weakest link in
the cable run that governs throughput. A network with
great cabling job can see a big performance reduction from
cheap patch cords. Since the network still works, many
times the customer isn't even aware of the loss of throughput."
Anixter has published its lab findings on cable performance
and recommendations for network and facilities managers in
a 54-page "Network Performance Guide." Direct Line
and CompStar have a limited supply of these - if you would
like your own copy,
e-mail us or complete the form below.
.
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CompStar Technologies is a leading Indiana-based provider of networking, technology, and communications services. With offices in Mishawaka (serving South Bend, Elkhart, Warsaw, Michigan City, Fort Wayne, Niles, St. Joseph, and Benton Harbor, Michigan) and Indianapolis, CompStar provides network design / support, network security, wireless networking, business telephone systems, VoIP (voice over IP), and cctv / video surveillance systems. CompStar is the Technology Division of Direct Line Communications, headquartered in Mishawaka, Indiana.
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