Is Gigabit Ethernet over Copper Picking Up Speed? - Page 3

 By Lynn Haber
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Despite the slow start for the copper-based 1000Base-T market, industry watchers expect widespread adoption. However, Gigabit Ethernet over copper is not suitable for all applications and companies are advised to consider the cabling infrastructure.

For example, vendors suggest that if a company is currently running Category 3 cabling, the next likely, and most cost-effective, upgrade, will be fiber. For this type of upgrade, fiber providers long-term investment and performance protection.

Category 5, 5e and 6 cabling can accommodate Gigabit Ethernet, says Bruce Tolley, manager of emerging technologies at Cisco Systems Inc., but, he adds, companies should test their Category 5 cable, in particular, before doing an upgrade. "Organizations should test for higher data rates on the pairs and data running on all pairs," he says.

In particular, Tolley notes, companies should test for far-end crosstalk and return loss. Far-end crosstalk defines noise on a wire pair at the far end from the transmitter, that is, the receiver. Return loss defines the amount of signal energy that is reflected back towards the transmitter due to impedance mismatches in the link, such as those caused by connectors.

According to Intel Corp., the 1000-Base T physical layer standard provides 1Gbps Ethernet signal transmission over four pairs of Cat-5 Unshielded Twisted Pair (UTP) cable. The standard covers cabling distances of up to 100 meters, or networks with a diameter of 200 meters. The 100-meter cabling distance is the safe limit for reliable transmission, and the diameter assumes 100 meters in two directions from a switch.

Companies may want to consider fiber, as opposed to copper, for applications in excess of 100 meters, or in situations where electromagnetic interference might be an issue.

"Given the current fiscal environment, if the copper cabling works, it makes sense for businesses to leverage their existing investments," says Tolley.

MIT has multiple types of copper wiring installed including Category 5, 5e and 6. "For Gigabit Ethernet we use a minimum of Category 5e or 6," says Coppeto. All cabling, he says, is tested upon installation to ensure that it can handle Gigabit speeds for future upgrades.

"What we hope to achieve with the Gigabit Ethernet upgrade is increased performance and that all the existing Ethernet equipment will continue to work the way it always hasno surprises," says Coppeto.

Lynn Haber writes on business and information technology from Norwell, MA.

This article was originally published on Oct 11, 2001
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