It's the next generation of copper
Is Level 7 wiring a solution looking for a problem?
By Stephen Lawton
Analyzing a building's wiring plant generally isn't
high on most IS managers' to-do lists, but as network
bandwidth needs and feeds increase, it becomes more of an issue. That
doesn't usually mean it will be necessary to rip out the existing wires
and pull new cable, but some contractors suggest that new buildings automatically
Category 5 UTP cables in their walls. Beyond that, questions remain about
whether you should install fiber-optic cabling at the same time.
Sending fiber to the desktop used to be considered overkill, but with
the introduction of gigabit Ethernet and all the other new applications
available to users, fiber to the desktop could become a reality to support
Decisions along these lines may hinge on timing. For example, the largest
cost of wiring isn't the cable itself but
the labor to install it, according to Ethan Harris, president of Harris
& Jeffries Inc., a developer of ATM and frame-relay source code for
embedded systems in Dedham, Mass.
When H&J recently upgraded its corporate facility's wiring from the
existing Category 3 cabling, the company pulled a bundle that included
Category 5 copper, Level 7 copper, single-mode fiber, and multimode fiber.
The reasoning was simple, Harris says. The cost of the materials is so
small compared to labor that pulling extra wires now ensures that the
right ones will be in the walls for any future need.
In a similar situation, Gail Glass, vice president of operations/technical
support at Chase Manhattan Mortgage
Corp. in Columbus, Ohio, also looked toward high-performance cable. His
company is among the first to install AMP Inc.'s four-pair UTP Netconnect
Quantum cabling, which is rated at 300MHz. (By contrast, standard
Category 5 cabling is rated at 100MHz.) The installation totals more than
one million feet of wiring and initially will
support an estimated 1,000 desktops.
Glass says he opted for the high-end copper wiring to the desktop and
an ATM-based fiber backbone so that his
users will be able to run virtually any application, from video on demand
or IP telephony to traditional business
He expects the cable to serve the company's needs for five to 10 years.
Enhanced Category 5 is not a standard--the
cable and connectors exceed Category 5 specifications, ostensibly for
greater performance and distance--but Glass
says it offers "more flexibility than fiber."
Tony Beam, AMP's director of systems marketing in Harrisburg, Va., claims
that the higher-performance cabling
provides a "cleaner signal" than standard Category 5 cable. Noise from
motors, elevators, fluorescent lights, and
microwave ovens are less likely to affect it, he says.
AMP targets new installations and sites where "significant rehabilitation"
is taking place. "If you expect to be in a
building for five or fewer years, this [cable] might not be the right
choice," Beam says.
Not surprisingly, wiring vendors urge that the need for high-performance
cabling is immediate, because many users
are beginning to implement gigabit Ethernet. Level 7 cable, developed
by Anixter Inc., is specified at twice the bandwidth of today's Category
5 cabling and achieves a 10 decibel attenuation-to-crosstalk ratio (ACR)
at 200MHz. Its higher ACR allows for more useable bandwidth, meaning that
users can get gigabit performance for the cable without exceeding the
cable's specifications, according to Anixter. This becomes an issue at
gigabit speeds, since the standard for 1000Base-T is still under development.
David Passmore, president of Decisys Inc., a consultancy in Sterling,
Va., says that most of the activity in high-end
cabling systems is just "marketing hype," but he sees value in what he
calls "engineered cabling systems" that include
specialized patch panels, punch-out blocks, and connectors.
He also says that there are no standards for many of the connectors that
tie networks together. "Category 5 wiring
that doesn't perform to specification is a far more serious problem" than
not having the highest-bandwidth cabling,
Passmore says. Engineered wiring systems solve that problem by assuring
that all wiring components--including
cables and connectors--meet the same performance criteria.
Nor are all systems integrators sold on high-performance cabling. "I
don't recommend Level 7 UTP [to clients] at this
time for two reasons," says Michal Grau, director of network-communications
services at Linc Network Systems Inc. in Cincinnati.
"There exists no way to test it to its claimed limits, and none of the
network equipment manufacturers that I work
with--Bay Networks [Inc.], Cisco [Systems Inc.], 3Com [Corp.], or Digital
[Equipment Corp.]--is developing any
hardware to utilize UTP cable past a total output of 100MHz across all
four pairs, even for ATM," Grau says.
"Right now, the only benefit I see for the Level 7 cable," Grau says,
"is that it allows for poor installation practices,
since it is more difficult to deform the twist relationships between the
pairs internally due to the bonding of the pairs
and the molding of the jacket."
Botched cabling is one of the biggest worries facing managers in this
area of networking, says Decisys'
Passmore. If installed incorrectly, Category 5 cabling can result in a
significantly underperforming network.
A common problem results from installers who strip and untwist more than
half an inch of wires at termination points.
Eliminating shoddy workmanship, Passmore says, could fix most performance
problems in twisted-pair-based
networks showing performance losses.