Category 5, or CAT5, was ratified in 1991. CAT5 has become obsolete in recent years, due to its limitations compared to CAT5e cables. Although the CAT5 cable is a good, solid cable for 10/100 Mbps LANs, the newer versions of CAT cables are significantly faster.
Category 5e, also known as Category 5 Enhanced, or CAT5e, is a network cable standard ratified in 1999. CAT5e cable offers significantly improved performance over the old CAT5 cable, including up to 10 times faster speeds and a significantly greater ability to traverse distances without being impacted by crosstalk.
CAT5e was specifically designed to have a reduced amount of crosstalk (the interference between cables when they are close to one another) compared to CAT5 cables. Crosstalk can still occur in CAT5e cables, but most of the time it does not result in any serious compromising of data.
You'll find existing CAT5 installations everywhere. It is commonly used to carry telephone or video signals in addition to Ethernet. CAT5e is an incremental improvement to CAT5 cable, designed to support full-duplex Fast Ethernet operation and Gigabit Ethernet.
If you have a lot of 10-Mbps equipment, CAT5 cabling will serve your needs. It also handles 100-Mbps Fast Ethernet transmissions very well.
CAT5e is a 100-MHz standard, though cables are available with up to 350-MHz capabilities. You can expect problem-free, full-duplex, 4-pair Ethernet transmissions over your CAT5e UTP.
The maximum distance you can run CAT5 is 100 meters, the same as CAT5e. If you need longer runs, active components such as routers or extenders can be used, provided they are CAT5 or CAT5e compatible.
The main differences between CAT5 and CAT5e can be found in the specifications. The performance requirements have been raised slightly in the new standard. CAT5e has stricter specifications for Power Sum Equal-Level Far-End Crosstalk (PS-ELFEXT), Near-End Crosstalk (NEXT), Attenuation and Return Loss (RL).
CAT5e has the capacity to handle bandwidth superior to that of CAT5. If you're running up against the performance limitations of a 100-Mbps network, you'll probably want to upgrade at least parts of your system to CAT5e or higher. CAT5e is backwards compatible and can be used in any application that would typically use CAT5.