Network Architecture Definition/Meaning:
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 control 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 tree-like 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.
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