Categories of LAN

A LAN comprises software that controls data handling & error recovery, hardware that produced and receives signals, and media that carry the signal. In order to ensure an appropriate communication among different devices, a set of rules called as protocol should be followed. This protocol governs the software & hardware design by defining the logical, electrical, and physical specification of network. Different LANs are illustrious by three characteristics:

• Their size
• Their transmission technology
• Their topology

IEEE has generated several standards for LAN, collectively known as IEEE 802. This includes CSMA/CD (carrier sense multiple access along collision detection), token bus, and token ring. The several standards differ at the physical layer and MAC (Multiple Access Control) sublayer however is compatible at the data link layer. The IEEE 802 standards have been accepted by ANSI as American National Standards, by NIST as government standards, and by ISO as international standards (called as ISO 8802). The standards are divided into different parts: 802.1 standards gives an overview of the definitions & standards of interface primitives, 802.2 explained the upper part of the data link layer, that uses the LLC (logical link control) protocol, parts 802.3 through 802.5 explained the three LAN standards, the CSMA/CD, token bus, and token ring standards respectively. Each of standards covers the physical layer & the MAC sub layer protocol. Added information might be found in Stallings, 1993b.