After reading this article you will learn about the two important types of classifications that are generally based on the transmission technology and on the scale and size of the geographical are covered. The classification based on transmission technology are: 1. Broadcast Networks 2. Point-to Point Networks.
1. Broadcast Networks:
Broadcast networks have a single communications channel that is connected to all the computers on the network. Messages transmitted are available to all the computers sharing the communications channel, although they may be meant for only one machine.
These messages, which are usually called packets, have an address field that specifies the computer for which it is intended. Upon receiving the message, each computer checks the address field and if the message is addressed to it, it receives and processes the packet.
If it is addressed to some other computer on the network, it ignores the packet. This process is analogous to candidates sitting in a room, waiting to face an interview.
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The announcer announces the name of the next candidate to be interviewed, so that the concerned candidate can walk into the room in which the interview is being held. This message is received by all the candidates present in the room, but only one candidate, for whom the message was intended, responds.
All the others ignore the message. However, there may be messages that are intended for all the computers in the network. This is usually achieved by using some previously agreed code in the address field of the packet. Upon encountering such a code in the address field, each computer receives the message and processes it.
Such message transmission is called broadcasting. This process can be further developed into different types of broadcast, for example, to computers in different groups. The broadcast can be meant for only certain selected groups.
The addressing scheme can easily be deduced in such cases. It is possible to use one bit to indicate such a broadcast in a packet address of n bits; the remaining bits being used to address the group. Any machine can make itself a part of one or more groups in the network. Such a type of broadcasting is usually called multicasting.
2. Point-to-Point Networks:
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Point-to-point networks are classified in a different manner. Machines may be interconnected in a different way. For example, several computers may be linked to each other directly or through other machines, so that different routes may be possible between any two machines.
The selection of the appropriate route at the time of message transmission could be an important issue that may have to be addressed at the time of designing the network. But the important factors on which this classification is based are the distances between the different computers in the network.