Networking Basics
models of computer networks
When did the first computer network was implemented ,????
We tend to believe that networks comes in to play after the micro computing industry was established on late 70's and early 80 's . but the computer network industry has its root back to the early days of computing industry. we normally treat network as interconnection of two or ore computers to share the data's and resources and this definition fits well to a modern day networking. but on the initial days of computing when systems occupies rooms and cost you a fortune, we cant think of interconnection of two or more computers. rather the initial networking model is called a host-terminal network. it is a model where there is one and only one computer and the computing power of that single system is shared by more than one input-output units called dump terminals. the terminals are just keyboard monitor extensions of the original machines to the d3sktop of each and every user and all the users believe that they have there own machine. it is a centrally managed centrally computed network environment.
this model become obsolete as micro computing become popular and the price of the microcomputer drops below that of a terminal. Naturally people begin to think that they don't need a network anymore. But after while they found that they still need a network to hare the costly components like hard disks and printers.
so one machine was assigned the main role which is rich on resources like hard disk printers and tape drive. other machines which lack these resources are connected to the main machine. this model is called the client-severer model of networking. it is a centrally managed but distributed computing network environment.
As we moved in to the 21st centaury all the resources become so cheap that all the machine can afford a hard disk drive. a group of computers that share the resources in a equal environment is called a peer to peer model of networking. it is a distributed managed and distributed computing environment.
Even though the computers become rich on resources and all the initial advantages of a client server network is gone , the attraction of a centrally managed computing environment is still there and for that reason the client server model will continue its lead as far as the companies who implements the network believes in a hierarchal model of networking.
The model of computer network depends on the operating systems used in the network. if you use UNIX as your operating system it will make the network a host-terminal model network. Novell NetWare as well as the Microsoft windows 2003 will create a client server model network. if you have 6 machines each running windows XP home connected to each other it will make a peer to peer network.
Geographical Aspect of a computer network
size is a simple concept to identify , even for a layman. so networks can be classified as small and big. the small networks are called LAN it can be two computers in a room , multiple computers in multiple rooms of a singe building or multiple building of a single campus. so that means the maximum size of a LAN can be up to CAN ( campus area network ).
the big networks can be as small as a group of computers in a city ( MAN) and it can be as big as our tiny planet or even beyond ( how about a Neptune to earth high speed data link ? )
the term LAN and WAN become such a cliché that everyone in the town knows the meaning . so it is more fashionable to say Wired network and Remote access network instead of LAN and WAN.
Topology....
The physical layout of the computer network is called topology. i.e. how the computers are interconnected in a network. back in the old days of computer networking computers were connected to a common line of information and this common line is called a bus . so it is called a bus topology
now we are not using bus topology for a LAN environment due to the reliability factors now we depends on something called a star topology. i.e. al the computers were connected to a junction box like equipment called a switch. star is the normal option available to a typical LAN.
Protocol
the rules and regulations of communication as well us the language of communications collectively called protocol. there are two types of protocol available , access protocol as well as communication protocol. it is also called hardware and software protocol respectively. the rules and regulations implemented as part of the data link equipments is called access protocol. the software side of the rules and regulations implemented as part of the operating systems is called the communication protocol
most popular hardware protocol available for LAN is Ethernet and the most popular communications protocol available is TCP/IP.
