ABOUT NETWORKING

WHAT IS NETWORKING ?

Networking is a connection of nodes via from media in which the nodes have the capability to send and receive data that is called networking.

NETWORK TOPOLOGY:-

WHAT IS TOPOLOGY ?

Topology is the method in which networks are physically connected With each other i.e called topology.

DIFFERENT TYPES OF TOPOLOGY:-

v      Mesh topology

v      Star topology

v      Bus topology

v      Ring topology

MESS TOPOLOGY:-

Ø      It is a fully connected topology.

Ø      In mess topology, every device has an dedicated point to point link to every other device.(point-to-point means connect two device directly Together.

Ø      In a mesh topology each device/PC is connected to every other device/PC in the network by its own cable, which means vast amounts of cables for any sizeable network.

Ø      The Mesh topology having separate cables for each connection if any one cable to break ,it does not incapacitate the entire system.

Ø      Every time you add a devices to a mesh network you have to run cables to each of the other devices.

Ø      The amount of cables you will need for a mesh network can be calculated by: CN = (D * (D-1)) / 2 (where CN is Cables Needed, and D is the amount of devices on the network)

Ø      If your network was going to have 4 devices then you would need 4 * 3 / 2 = 6 cables

Ø       The problems come with a large network, imagine a 40 device network: 40 * 39 / 2 = 780 cables

Ø      When you need to add a single device to a Mesh network the job can be very complex, for example if you had a network of 15 devices, to add one device would mean adding 15 cables to the network.

ADVANTAGES OF MESH TOPOLOGY:-

Ø       Mess topology is more reliable.

Ø      It is more flexible.

Ø      It is very expensive.

Ø      It is more secured and privacy is well maintained.(when every Message travels along a dedicated line, only the intended recipient Sees this message).

DISADVANTAGES OF MESH TOPOLOGY:-

Ø      It is costlier.

Ø      The amount of cabling and the no. of I/O ports required, that’s why installation and reconnection are difficult.(because every device connected to other device).

STAR TOPOLOGY:-

Ø         In a Star topology each devices has a dedicated point-to-point link only to

central controller such as a Hub or Switch or router.

Ø      The devices are not directly linked to one another. Here data travels through

the hub to all other devices. i.e cotroller acts as an exchange.

Ø      If one device wants to send data to another  device, that time first device

sends the data to the controller, which then relays the data to the other

connected device.

Hub are two types-

n      Active hub

n      Simple hub

Active hub :- it release the data and refresh the data.

Simple hub:- it  only release the data.

Ø      In a Star topology, if one   device/cable failure, it will not affect the another  network .

Ø      If centralising device or server failure that time all devices fails.

A star network  requires more cable.

Ø      Physically adding new devices to a Star network is very simple compared to any of the other topologies.

Example-In our college computer lab is use in star topology.

ADVANTAGES OF STAR TOPOLOGY:-

Ø      It is much easier to modify or add new computers to a star network without disturbing the rest of the network.

Ø      It is reliable.

Ø      It is flexibility.

Ø      The failure of a single device or cable does not bring down the entire network.

Ø      It is easy to install and reconfigure (that is each device needs only one link and one i/o to connect it to any no. of others).

DISADVENTAGES OF STAR TOPOLOGY:-

Ø      If the central hub fails, the whole network fails to operate .

Ø      It is costlier .

Ø      It is less expensive than a mesh topology.

USES OF STAR TOPOLOGY:-

Ø      It is used in local-area-network(LAN).

Ø      High speed LAN often use a star topology with a central hub.

BUS TOPOLOGY:-

Ø      Bus topology is a multipoint structure.

Ø      Bus consists of a single linear cable called a trunk/backbone link all the devices in a network.

Ø      A Bus topology can be both Physical and Logical .

Ø      Network nodes are connected to the bus cable by drop line and tapes.

1. Drop lines – it is connection between a node and the main cable.

2. Taps – A tape is a connector either splices into the main cable or punctures

the sheathing of a cable to create a contact with the metallic core.

Terminators should be applied to both ends of the longest path.

Ø      Data is sent to all computers on the trunk. Each computer examines every packet on the wire to determine who the packet is for and accepts only messages addressed to them.

Ø      Bus is a passive topology which means only

One computer at a time can send a message.

Ø      The problems can come when  adding a new device to an existing Bus topology network.

ADVANTAGES OF BUS TOPOLOGY:-

Ø      It is easy to use and understand.

Ø      Less no. of cable required.

Ø      It is inexpensive simple network.

Ø      It is easy to installation.

DISADVANTAGES OF BUS TOPOLOGY:-

Ø      It is very difficult to reconnection and fault isolation.

Ø      It can be difficult to add new device.

Ø      It require modification or replacement of the backbone when adding new device.

Ø      If cable break or loose connector or fails, the whole network not working.

USES:-

Ø      Bus topology  was one of the first topology Used in the design of early local area

network(LAN).

Ø      Ethernet LAN can be use a bus topology.

RING TOPOLOGY:-

Ø      Computers are connected on a single circle of cable.

Ø      In ring topology each device has an dedicated point-to-point connection only the two devices on the either side of it.

Ø      The signal is passed along the ring in one direction from device to device, until it reachers the destination.

Ø      In a ring, a signal is circulating at all times.

Ø      Here signal is circulating by anticlockwise.

Ø      Each device in the ring incorporates a repeater.

Ø      When a device receives receives a signal intended for another devices. its repeater regenerates the Bits and passes them along.

Ø      If one device does not receive a signal within a specified period ,it can issue an alarm.  The alarm alerts the network operator to the problem and its location.

Ø      If one device/cable fails then the whole network goes down.

Ø      Adding a new device to an existing physical Ring network can be complicated.

Arbitrary mechanism means token.

Ø      Here token ring or FDDI(fiber distributed data interface) used.

Ø      Here no termination  is required because it is a ring. there is no end of its ring.

Ø      Token passing is used in token ring networks.

Ø      The token is passed from one computer to the next, only the computer with the token can transmit.

Ø      This topology is faster.

Ø      This type of topology can be found in peer-to-peer network.

ADVANTAGES OF RING TOPOLOGY:-

Ø      It is relatively easy to install and reconfigure.

Ø      It is more reliable.

Ø      Security is less.

Ø      Cost is less.

Ø      It is more reliable.

DISADVANTAGES OF RING TOPOLOGY:-

Ø      It is unidirectional.

Ø      If failure of one computer on the ring can affect the whole network.

Ø      It is difficult to troubleshoot a ring network

Ø      Adding and removing devices disrupts the network.