The largest computer network, the Internet, has more than one billion users. In communication system we are using wired and wireless trancemission media, the system connects small and large computers. It allows users to share an desired amount of imformation including text, images, audio, and video. It enables uders send messages to each other. Exploring this extensive system is the major goal of this Blog that provide as a benifitial notes.
1. OVERVIEW OF THE INTERNET
We are discuss the Internet, a system that interconnects billions of computers in the world, we think of the internet not a single network, but as an internetwork, a combination of networks. Further we will know what is the network and how it is work for communication in all Computer Network tag.
1.1 Networks
A network is the interconnection of a set of devices capable of communication. A device can be a host such as a large computer, desktop workstation, celluler phone or security system. A device can also be a connecting device such a router which connects the network to other networks, a switch connect device together, a modem that changes the form of data and so on.
1.2 Local Area Network
A Local Area Network(LAN) is usually privately owned and connects some hosts is a single office, building or campus. Depending on the needs of an organization. Each host in a LAN has an identifier, an address, that uniquely defines the host in the LAN.
1.3 Wide Area Network
This is also use for communication, but however there are some differ to LAN, a WAN has a wider georaphical span, spanning a town, a state, a country or ever the world. A WAN is normally created and run by communication companies and leased by an organition that uses.
Today LAN and WAN are connected to one another not single. When two or more networks are connected, they make an internetwork or internet.
Example:- Let us an organization has two offices, one on East India and the other on the West India. Each office has a LAN that allows all employees in the office to communicate with each other. If both offices want to communicate to each other then possible to WAN from a service provider, such as a telephone company, and connects the two LANs.
when a host in the west India office sends a message to another host in same office, the router block the message, but the switch directs the message to the destination. On the other hand, when a host on the west India sends a message to a host on the east India, router R1 routes the packet to router R2 and the packet reaches the destination.
Here we can defining two types of Switch first one is the Circuit-Switched-Network and second Packet-Swiched-Network.
Circuit-Switched-Network
In this, dedicated connection, called circuit switch, is always available between the two end systems. We have used telephone set instead of computers, becuase circuit switching was very common in telephone networks in the past generation. But today part of telephone network is a packet-switched-network.
Packet-Switched-Network
It is also a connection between two ends communication systems and is done in blocks of data called packets. In other word when connect computers between two end point then we see the exchange of individal data packets between the two computers. Allow to make the switches fuction for both storing and forwarding because a packet is an indepandent entity.
