A computer network is basically defined as the interconnected collection of autonomous computers. The word ‘interconnected’ here means that the computers are able to exchange the information between them. The word ‘autonomous’ here means that the interconnected computers do not bear a master slave relationship that is one computer does not control the other. Further there are various types of computer networks. Computer networks are basically classified under three categories:
1.Transmission Technology
2.Size
3.Topology
Types of Computer Networks on the Basis of Transmission Technology
1.Broadcast Networks
It is one of the most popularly used computer networks. In this type of network, there exists a single communication channel or cable to which all the machines are connected on the network. When a short message, known as packet, is send by one machine, it is received by all other machines on the network. An address field is specified within each packet which tells to which machine the packet is actually intended. On receiving the packet, each machine examines the address field of the packet. If the packet is intended to the machine, it processes the packet. However, if the packet is intended to some other machine, it is just ignored. Usually, smaller or geographical localized networks make use of broadcast networks.
2.Point-to-Point Networks
In case of the point to point networks, it consists of many connections between individual pair of machines. The packet on this type of network has to first visit one or more intermediate machines to go from source to destination. As a rule, larger networks often use point-to-point networks.
Types of Computer Networks on the Basis of Size
1.Local Area Networks (LAN’s)
Local Area Networks are widely used to connect personal computers and workstations in company, schools, colleges, factories etc. to share the resources like printers and exchange information. LAN’s are privately owned networks within a single building or campus of a few kilometers in size. LAN’s basically employs broadcast transmission technology. Traditional LAN’s run at speed up to 10 to 100 megabits/second. Newer LAN’s operate at higher speeds, up to hundreds of megabits/second. IEEE 802.3 or Ethernet is the best example of LAN.
2.Metropolitan Area Networks (MAN’s)
It is a network that covers a larger area as compared to LAN. Metropolitan Area Network is basically a bigger version of LAN normally using the same technology. It can be either public or private. It may cover a group of nearby corporate offices or the entire city. A standard has been adopted for MAN, which distinguishes it from other networks. It is called Distributed Queue Dual Bus (DQDB) . It consists of two unidirectional buses to which all the computers are connected. Each bus has a device that initiates the transmission activity called the head-end. Traffic coming to the right of sender follows the upper bus while the traffic coming to the left of the sender follows the lower bus.
3.Wide Area Networks (WAN’s)
It is the largest of all the networks in terms of size. It covers a large geographical area, usually a country or a continent. Internet is the best example of Wide Area Network. It contains a collection of machines for running the user programs. These machines are known as the hosts. The hosts are connected by communications subnets. The main purpose of the subnet is to carry the messages from host to host. The subnets consist of two distinct components: transmission lines and switching elements. Transmission lines moves the bits while the switching elements connect two or more transmission lines. Routers and transmission lines (not the hosts) together constitute the subnet. Such a network when extended forms the WAN.
Types of Computer Networks on the Basis of Topology
1.Bus Topology
In case of the linear cable or bus topology, at any instant only machine is the master and is allowed to transmit message or packet of information. All the other machines must refrain from sending at this particular moment. However in case of any conflict when two or more machine wants to transmit the message simultaneously, an arbitrary mechanism is employed.
2.Ring Topology
In case of the ring topology, each bit moves around on its own, not waiting for the rest of the packet to which it belongs.
1.Transmission Technology
2.Size
3.Topology
Types of Computer Networks on the Basis of Transmission Technology
1.Broadcast Networks
It is one of the most popularly used computer networks. In this type of network, there exists a single communication channel or cable to which all the machines are connected on the network. When a short message, known as packet, is send by one machine, it is received by all other machines on the network. An address field is specified within each packet which tells to which machine the packet is actually intended. On receiving the packet, each machine examines the address field of the packet. If the packet is intended to the machine, it processes the packet. However, if the packet is intended to some other machine, it is just ignored. Usually, smaller or geographical localized networks make use of broadcast networks.
2.Point-to-Point Networks
In case of the point to point networks, it consists of many connections between individual pair of machines. The packet on this type of network has to first visit one or more intermediate machines to go from source to destination. As a rule, larger networks often use point-to-point networks.
Types of Computer Networks on the Basis of Size
1.Local Area Networks (LAN’s)
Local Area Networks are widely used to connect personal computers and workstations in company, schools, colleges, factories etc. to share the resources like printers and exchange information. LAN’s are privately owned networks within a single building or campus of a few kilometers in size. LAN’s basically employs broadcast transmission technology. Traditional LAN’s run at speed up to 10 to 100 megabits/second. Newer LAN’s operate at higher speeds, up to hundreds of megabits/second. IEEE 802.3 or Ethernet is the best example of LAN.
2.Metropolitan Area Networks (MAN’s)
It is a network that covers a larger area as compared to LAN. Metropolitan Area Network is basically a bigger version of LAN normally using the same technology. It can be either public or private. It may cover a group of nearby corporate offices or the entire city. A standard has been adopted for MAN, which distinguishes it from other networks. It is called Distributed Queue Dual Bus (DQDB) . It consists of two unidirectional buses to which all the computers are connected. Each bus has a device that initiates the transmission activity called the head-end. Traffic coming to the right of sender follows the upper bus while the traffic coming to the left of the sender follows the lower bus.
3.Wide Area Networks (WAN’s)
It is the largest of all the networks in terms of size. It covers a large geographical area, usually a country or a continent. Internet is the best example of Wide Area Network. It contains a collection of machines for running the user programs. These machines are known as the hosts. The hosts are connected by communications subnets. The main purpose of the subnet is to carry the messages from host to host. The subnets consist of two distinct components: transmission lines and switching elements. Transmission lines moves the bits while the switching elements connect two or more transmission lines. Routers and transmission lines (not the hosts) together constitute the subnet. Such a network when extended forms the WAN.
Types of Computer Networks on the Basis of Topology
1.Bus Topology
In case of the linear cable or bus topology, at any instant only machine is the master and is allowed to transmit message or packet of information. All the other machines must refrain from sending at this particular moment. However in case of any conflict when two or more machine wants to transmit the message simultaneously, an arbitrary mechanism is employed.
2.Ring Topology
In case of the ring topology, each bit moves around on its own, not waiting for the rest of the packet to which it belongs.
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