NETWORK SOFTWARE

Network Software



· Computer network is designed around the concept of layered protocols or functions.
For exchange of data between computers, terminals or other data processing devices, there is data path between two computers, either directly or via a communication network.

· Following factors should be considered.

1. The source system must either activate the direct data communication path or inform the communication network to identity the desired destination system.
2. Provide for standard interface between network functions.
3. Provide for symmetry in function performed at each node in the network. Each layer performs the same functions as its counterpart in the other node of network.

· The network software is now highly structured.

Protocol Hierarchies





· Most of all networks are organized as a series of layers, each one built upon the one below it. Because of layer, it reduces the design complexity.

· In layer protocols, a layer is a service provider and may consist of several service functions. Function is a sub-system of a layer.

· Each subsystem may also be made up of entities. An entity is a specialized module of a layer or subsystem.

· Name of the layer, total number so layer, function and content of each layer differ from network to network.

· Protocols are the rules that govern network communication.

· Layer n on one node carries on a conversation with layer n on other node.

· The entities comprising the corresponding layers on different machine are called peers.

· The actual data flow in from upper layer to its below layer and the from physical medium to destination layer.

· Between each pair of adjacent layers is called interface. The interface defines which primitive operations and services the lower layer offers to the upper one.
· A set of layers and protocols is called a network architecture.