Networking

NETWORKING

What is Networking?

A computer network allows computers to communicate with many other computers and to share resources and information.

Advantages of Networking

Networking facilitates sharing of data among various computers.

The programs and software fed in the central computer can be simultaneously used by all terminals.

Various hardware resources like Printer, Scanner, Plotter etc. that are connected to the central computer can be used by all the terminals.

The Overall cost of set-up reduces. 

Network classification:

The following list presents categories used for classifying networks.

Wired Technologies

Twisted-Pair Wire - This is the most widely used medium for telecommunication. Twisted-pair wires are ordinary telephone wires which consist of two insulated copper wires twisted into pairs and are used for both voice and data transmission. The use of two wires twisted together helps to reduce crosstalk and electromagnetic induction. The transmission speed ranges from 2 million bits per second to 100 million bits per second.

Coaxial Cable - These cables are widely used for cable television systems, office buildings, and other worksites for local area networks. The cables consist of copper or aluminum wire wrapped with insulating layer typically of a flexible material with a h'gh dielectric constant, all of which are surrounded by a conductive layer. The layers of insulation help minimize interference and distortion. Transmission speed range from 200 million to more than 500 million bits per second.

Fiber Optics — These cables consist of one or more thin filaments of glass fiber wrapped in a protective layer. It transmits light which can travel over long distance and higher bandwidths. Fiber-optic cables are not affected by electromagnetic radiation. Transmission speed could go up to as high as trillions of bits per second. The speed of fiber optics is hundreds of times faster than coaxial cables and thousands of times faster than twisted-pair wire.

Wireless Technologies :

Terrestrial Microwave - Terrestrial microwaves use Earth-based transmitter and receiver. The equipment look similar to satellite dishes. Terrestrial microwaves use low-gigahertz range, which limits all communications to line-of-sight. Path between relay stations spaced approx. 30 miles apart. Microwave antennas are usually placed on top of buildings, towers, hills, and mountain peaks.

Communications Satellites - The satellites use microwave radio as their telecommunications medium which are not deflected by the Earth's atmosphere. The satellites are stationed in space, typically 22,000 miles above the equator. These Earth-orbiting systems are capable of receiving and relaying voice, data, and TV signals.

Types of networks

Below is a list of the most common types of computer networks in order of scale.

Local area network

A local Area Network (LAN) is a computer network covering a small physical area, like a home, office, or small group of buildings, such as a school, or an airport.

Metropolitan area network

A metropolitan area network (MAN) is a network that connects two or more local area networks or campus area networks together but does not extend beyond the boundaries of the immediate town/city. Routers, switches and hubs are connected to create a metropolitan area network.

Wide area network

A wide area network (WAN) is a computer network that covers a broad area (i.e. any network whose communications links cross metropolitan, regional, or national boundaries

Network topology

Network Topology is the way the nodes are connected in a network. Some of the common network topologies are

Linear Bus Topology, Star Topology , Ring Topology .

Linear Bus Topology

When all terminals are connected one after another in a straight line, the topology is referred to as bus topology. The server is connected at one end of the arrangement of nodes.

                                                    

Advantages

It is easy to install. Low cabling cost Disadvantages:

1.       At a time only one message can travel through the backbone cable.

2.       Since all the nodes attempt to put their message on the common line, the possibility of collision is high.

Ring Topology

In this topology each node is connected to only two neighboring nodes through cables. A node receives data from one neighbouring node and transmits it to the next node.

 

Advantages

Since at a time only one node transmits data, there is no chance of collision. 

Disadvantages:

Even if a simple terminal fails, the whole network has to be shut down. Its layout is more complicated than Bus topology.

Star Topology

In this all the nodes are directly connected to the server. Therefore it is easy to add or remove any node.

 

 

Advantages

1.    If a node down, the working of other nodes is not affected.

Disadvantages:

1.    If the server fails the complete network goes down.

Basic hardware components

All networks are made up of basic hardware building blocks to interconnect network nodes, such as Network Interface

Cards (NICs), Bridges, Hubs, Switches, and Routers

Network interface cards

NIC provides the hardware interface between a computer and a network. Some NIC cards work with wired connections while others are wireless.

Repeaters

A repeater is an electronic device that receives a signal and retransmits it at a higher power level, or to the other side of an obstruction, so that the signal can cover longer distances without degradation. In most twisted pair Ethernet configurations, repeaters are required for cable which runs longer than 100 meters.

Hubs

A network hub contains multiple ports. When a packet arrives at one port, it is copied unmodified to all ports of the hub for transmission. The destination address in the frame is not changed to a broadcast address.

Bridges

A bridge device filters data traffic at a network boundary. Bridges reduce the amount of traffic on a LAN by dividing it into two segments. Bridges inspect incoming traffic and decide whether to forward or discard it.

Switches

A network switch is a small hardware device that joins multiple computers together within one local area network (LAN). Network switches appear nearly identical to network hubs, but a switch generally contains more intelligence (and a slightly higher price tag) than a hub. Unlike hubs, network switches are capable of inspecting data packets as they are received, determining the source and destination device of each packet, and forwarding them appropriately.

Routers

Routers are physical devices that join multiple wired or wireless networks together.