Quick fix can cure Gigabit Ethernet/cable headache

Users looking to upgrade their server or wiring closet switches to Gigabit Ethernet might want to hold off on ordering fiber optic cable, or even advanced Category 6 unshielded twisted pair wiring, says one expert.

"You don't have to rip out your legacy [Category 5] wiring to run Gigabit Ethernet," says Michael O'Connor, LAN specialist for Hubbell Premise Wiring in Stonington, Conn. "Nothing says you have to put Category 6 or fiber in today."

O'Connor has overseen wiring installations for many large enterprises, and is also involved in IEEE standards development for network cabling specifications.

There are limitations to some older copper cabling installations, O'Connor adds.

"The requirement that copper Gigabit can only run 100 meters is in stone," he says, so for interbuilding connectivity, fiber is still the answer. Inside a building, older Category 5 wire may also not support Gigabit Ethernet, depending on the quality of the cable.

O'Connor says users can test to see if their older wiring will support Gigabit Ethernet by using a standard network testing device from Fluke or Hewlett-Packard using the IEEE TSB95 field testing specification.

The test, O'Connor says, measures the levels of interference, cross-talk and packet loss that occur between two points in a network - usually between an RJ-45 wall jack at an end user's desk and the cable termination, or punch-down, rack inside a wiring closet where switches reside.

According to O'Connor, failures of this test are usually the result of low-quality patch cables between a workstation and wall jack, or in a punch-down rack.

"Ninety percent of the time, this is the case," O'Connor says. "Then all you do is remove the patch cord and put in a known Category 5e, or even Category 6 [patch] cable, [which are backwards-compatible]. This typically will resolve your problems, from what I've seen."