Category 5e Overview
Enhanced Category 5
The Category 5e standard for structured cabling was defined and completed in 2000 by the Telecommunications Industry Association/ Electronic Industries Alliance (TIA/EIA) creating an "enhanced" version of the existing Category 5 standard. Additions to the Category 5 standard include transmission performance specifications for Return Loss, NEXT, and PS EL-FEXT as well as instructions for testing procedures.
Fast Ethernet (100BASE-TX) achieves 100 Megabits per second (Mbps) operation by using two pairs: one for transmit, one for receive. Newer technologies look to use the remaining two pairs as a way to achieve higher speeds across the existing data cable. Essentially, the Category 5e tests ensure performance over all 4 pairs within a cable, allowing for the implementation of higher-speed applications such as Gigabit Ethernet. For example 1000BASE-T (IEEE 802.3 Ethernet standard for Gigabit Ethernet on Category 5 copper, ratified in June 1999), requires the use of all 4 pairs. The 1 Gigabit per second (Gbps) speed is calculated by adding the speed provided by each of the 4 pairs within the cable (250 Mbps x 4 pairs = 1000 Mbps OR 1 Gbps).
The current 1000BASE-T gigabit Ethernet standard can be implemented without any modification to a structured cable network that follows the Category 5e specification. This is not necessarily the case with Category 5 installations which have never been tested for performance over 4 pairs. These existing networks may require modification or replacement before they are able to take advantage of higher-speed applications.
* Information provided by Gigabit Ethernet Alliance, and TIA/EIA