The performance of these technologies is related to issues such as the integrity of the cabling infrastructure, cable length, the quality of connecting hardware, the number of connectors within a segment, and the number of wire pairs used during transmission. The standard, which has been in effect for a number of years, is being revised. Many of the proposed revisions are necessary to meet the increasingly stringent requirements of today's networks, such as running higher-speed technologies like Gigabit Ethernet over copper cabling. In the past, there's been extensive debate over copper cabling's capacity to support higher-speed technologies. However, if you plan to run higher-speed technologies over copper, you should be aware of several issues.
Attenuation is the loss of power that occurs in a signal as it travels across the cable.
In NEXT, the signal crosses over one wire pair to an adjacent pair, with the crossover occurring near the transmitter. One cause of NEXT is cabling that has been installed with an insufficient bend radius. This can press wire pairs flat inside the cabling, or untwist them. Untwisting of the wire pairs can also cause impedance mismatch. The first 50 feet or so of a cable run are particularly susceptible to NEXT, a fact that should be kept in mind during the cable planning, installation, and management phases.