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Computer Network

A computer network is an interconnection of two or more computer that are able to exchange information. The computer may be connected via any data communicated link, like copper wires, optical fibers, communication satellites, or radio links. The computer connected to the network may be personal computer or large main frames. The computer in a network may be located in a room, building, city, country, or anywhere in the world.

Network Topology/LAN Topology

A network topology is the arrangement of computer, cables, and other components on a network or

a map of geometrical shape of physical network of computer is network topology. Or the term topology refers to the manner and complexity of interconnection between nodes on a network. It is the logical way of explaining how computer are connected each other and show physically how they are linked.

There are different type of network topology that are use in a network.

The topology commonly used in LAN are Bus topology, Star

Topology, and Ring topology.

                      Bus Topology     

A topology in which all of the computer in a network are attached to the continuous cable or segments that connects them in a straight

line is called bus topology. In a bus topology a set of clients are connected through a shared communication line called a bus. Term-

inators are used at the both end of cable to absorb the signals so it doesn't reflect back across the bus.

Bus topology are simplest way to connect multiple clients but often have problem when two clients wants to transmit at the same time on the same bus. System which is bus network architecture normally has some scheme of collision handling or collision avoidance. For communication on the same bus often using carrier sense multiple access or the presence of bus master which control access to the shared bus resource.

Advantages

1)It is simple, reliable, easy to use and easy to understand.

2)Failure of one computer does not affect other.

3)It work well when you have a small network.

4)Easiest network topology for connecting computers or peripherals in a linear fashion.

5)Requires less cable length than a star topology.

Disadvantages

1)Difficult to identify the problems if the whole network goes down.
2)It can be heard to troubleshoot individual device issues.
3)Not great for large networks.
4)Terminators are required for both ends of the mean cable.
5)Additional devices slow the network down.

                                      Ring Topology

  Ring topology, also known as Ring Network, is a type of network topology where each node is exactly connecting to two other nodes, forward and backward, thus forming a single continuous part for signal transmission. In this topology computers are arranged in a circle and data moves around the ringing one direction.Each node in the topology share a ring bypassing a token that specifies whose turn it is.

Advantages

1)All data flows in one direction, reducing the chance of packet collisions.
2)A network server is not needed to control network connectivity between each workstation.
3)Data can transfer between workstation shuts down.
4)Additional workstation can be added without impacting performance of the network.
5)Because of every computer is given equal access to the token, no one computer can monopolize the network.

Disadvantages

1)All data being transferred over the network must pass through each workstation on the network, which can make it slower than a star topology.

2)The entire network will be impacted if one workstation shuts down.

3)The hardware needed to connect each workstation to the network is more expensive than Ethernet cards and hubs/switches.

4)More cabling is needed than a bus network.

5)Very hard t find out errors.

                                  Star topology

A network topology in which each of the devices and computers on a network connect to a central hub or switch is called star topology.
In a star topology network all cables run from the computer to the central location, where they are all connected by a device called a hub. Stars are used in concentrated network, where the end points are directly reachable form the central location. A star network topology is best suited for smaller network and works efficiently when there are a limited number of nodes. One has to ensure that the hub or the central computer is always working and extra security is added to the hub because it is the heart of the network.

Advantages

1)It is easy to remove and add new computers to star network without disturbing the rest of the network.

2)Single computer failure does not necessarily bring down the whole star network. The hub can detect the problematic computer or network cable and allow the rest of the network to continue functioning.

3)Centralized control.

4)Higher security.

Disadvantages

1)If the central hub fails, the whole network fails or stops.

2)It costs more to cable a star network because all network cable must be pulled to one central point

requiring more cable than other network topology and cost of hub.

3)Data collision rate is high.