One of the most important decision when installing an office network system is the selection of the right cabling system. In India the cables of choice for Local Area Network (LAN) are high performance Unshielded Twisted Pair (UTP) cables.

However, there are still some applications in which Shielded Twisted Pair (STP) cables are utlised. For instance in many installations require the use of Fiol Twisted Pair (FTP) cables, which includes a polyethylene insulated pair shielding and overall shielding.
Industry standards have been established to determine the transmission performace of such cables.

These performance categories and the applications for which they are described below :

Category 1 : These cables are typically used for voice and low-speed data transmission applications. Typical transmission rates are 1 and 4 Mb/s.
Category 2 : These cables are also used for voice and data transmission applications, with rates of up to 10 Mb/s.
Category 3 : While still used for voice and data, these cables meet the performance characteristics necessary for high-speed LAN system. The performance specification of cables of this category, which are capable of transmission speed of up to 16 Mb/s, has been increased beyond earlier standards to 20 MHz.
Category 4 : This cable category represents the ultimate data transmission performance possible with a UTP cable. The transmission rates are up to and including 100 Mb/s, at 100 MHz. To achieve this rate, all of the characteristics of the cables must be of the highest possible tolerances.
Category 5 : Specifications for this category are still under evaluation. It is expected that the frequency will reach 300 Mhz.