Category 5 and 5e
Category 5 (CAT5) cabling is good, solid cable for 100-Mbps LANs. The Category 5 standard has been around since 1991, so it’s well established. You’ll find existing Category 5 installations everywhere. What can Category 5 cable do, and what can’t it do?
If you still have a lot of 10-Mbps equipment, CAT5 cabling will serve your needs. It also handles 100-Mbps Fast Ethernet transmissions very well.
But if you’re running up against the performance limits of a 100-Mbps network, you’ll probably want to upgrade at least parts of your system fairly soon to Category 5e (CAT5e) or higher.
Category 5e: The improved Category 5
Category 5e, also known as Enhanced Category 5, or CAT5e, was ratified in 1999. It’s an incremental improvement designed to enable cabling to support full-duplex Fast Ethernet operation and Gigabit Ethernet.
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) than those for CAT5. Like CAT5, CAT5e is a 100-MHz standard, but it has the capacity to handle bandwidth superior to that of CAT5. With these improvements, you can expect problem-free, full-duplex, 4-pair Ethernet transmissions over your CAT5e UTP.
Category 6 and 6a cables