what is computer network ?

Network Functions:

The various user applications impose different requirements on the services provided by the network in terms of accuracy of transmission, reliability of service, volume of information that can be transferred. transfer delay and cost.

The basic function of a network is to transfer information between a source machine and a destination machine.

The following is a list of functions that a network must carry out:

• Basic user service i.e. the primary services that are provided by the network to its users.
• Switching approach i.e. the means of transferring information between different communication lines.
• Transmission system i.e. the means for transmitting information across a physical medium.
• Routing i.e. the means for identifying/determining the path across the network.
• Multiplexing i.e. the means for connecting multiple information channels into shared connection lines.
• Information representation i.e. the format of information handled by the network.
• Addressing i.e. the means for identifying the end system (Terminal) that connects to the network.

The essential network functions are characterised by how information Is organised for transmission, multiplexing, routing and switching in a network.

The services that are provided to the user are build on the basic transfer capability of a network.

There are three types of networks in existence which use the different types of switching techniques :

• Telegraph network operation is based on message switching which provides the transfer of text messages called telegrams
• Telephone network operation is based on circuit switching which provides the transfer of voice messages.
• Internet operation is based on packet switching which provide the transfer of digital data.