A computer Network is a number of computers linked together to allow them to share resources and information.
Stand-alone computer is a computer which is not connected to any other computer.
Types of Networks - (based on the area covered)
LAN – Local Area Network
MAN – Metropolitan Area Network
WAN – Wide Area Network (Internet)
Advantages of Computer Networks:
- Communication - Users can communicate each other if the computers are connected.
- Sharing Resources - Can share expensive Hardware like Printer, Scanner. Etc.
- Sharing Software - Expensive software can be shared. (No need to install a software on all computer)
- Sharing Data- a single instance of all file can be kept on one computer and can be accessed by all other computers in the network.
Requirement for making a network
- Cable/wires for connecting computers
- NIC – Network Interface Card
- A software to enable networking
A typical network may contain the following:
- File Server
When you are making a network you can connect the computers in several different ways. These ways of connecting computers are called as toplogy. Each method has its own advantages and disadvantages.
In other words, the physical layout of cable is called as Topology.
Examples for network topology are:
- BUS Topology
- RING Topology
- STAR Topology
- TREE Topology
- HYBRID Topology
1. BUS TOPOLOGY
In a bus topology all computers are connected to a long cable.
Advantages of BUS topology:
- Less cable length needed
- Easy to design & install
Disadvantages of BUS topology:
- If cable breaks entire network stops working
- If number of workstations are high performance will be slow
2. RING TOPOLOGY
In a ring network all the computers are connected in a circular fashion
Advantages of RING topology:
- Cheap, as less cable length is required
Disadvantages of RING topology:
- If single machine switched off then the network doesn't work
3. STAR TOPOLOGY
A star network is one in which all computers are directly connected to a central device called Hub/Switch.
Advantages of Start network
- More reliable
- Faster – because of less data collision
- If one connection fails the entire network is NOT affected
- Easy troubleshooting (If one computer cannot access network we have to check only that computer and the cable connecting that computer with the switch)
Disadvantages of Star network
- Expensive – because more cable length required
- If hub/switch fails the entire network fails
4. MESH TOPOLOGY
It is a network in which each computer is directly connected to all other computers in the nework.
5. TREE TOPOLOGY
It is a network which combines the features of bus and star networks. A group of star-topology networks are connected to a bus network.
6. HYBRID TOPOLOGY
It is a network that combines more than one topology.
In the above diagram there are three small networks, (a bus, star and ring) connected together to form a large network. This large network is called as a Hybrid Network