network architecture

network architecture The design and implementation of a communication network with respect to its communication disciplines and its interconnection topology. Network architecture deals explicitly with the encoding of information, its transmission, error detection, error correction, and flow control, techniques for addressing subscribers on the network, analysis of network performance under abnormal or degraded conditions (such as missing communication lines or improperly functioning switching nodes), etc. Examples of generalized network architectures are OSI (open systems interconnection, an architecture propounded by the ISO) and SNA (systems network architecture, proposed and supported by IBM).

Interconnection topology is also considered a part of network architecture. There are three generic forms of topology: star, ring, and bus. Star topology consists of a single hub node with various terminal nodes connected to the hub; terminal nodes do not interconnect directly. By treating one terminal node as the hub of another star, a treelike topology is obtained. In ring topology all nodes are on a ring and communication is generally in one direction around the ring; some ring architectures use two rings, with communication in opposite directions. Various techniques (including time division multiplexing, token passing, and ring stretching) are used to control who is allowed to transmit onto the ring. Bus topology is noncyclic, with all nodes connected; traffic consequently travels in both directions, and some kind of arbitration is needed to determine which terminal can use the bus at any one time; Ethernet is an example. Hybrids that mix star and ring topologies have been employed.

A special area of network architecture is involved with the necessary disciplines required of some of the newer network architectures (see ring network, token ring, Ethernet).