TOPOLOGY NOTES

  Write the differences between star and bus topology of network?

Star Topology	Bus Topology
In a star topology, Each device has a dedicated point-to-point connection to a central controller, called a hub. The devices are not directly linked to each other.	In a bus topology, One long cable acts as a backbone to link all the devices in the network.
The controller acts as an exchange. If one device wants to send data to another, it sends the data to the controller which then relays the data to the other connected device.	In bus topology, nodes are connected to the bus cable by drop lines and taps. The drop line is a connection running between the device and the main cable. A tap is a connector. In bus topology, signal always travelling along backbone, so some energy transfer into heat, so there should be limited number of nodes in bus topology.
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 WHAT ARE THE VARIOUS TYPES OF CONNECTION AVAILABLE IN NETWORK.

In computer networking system mainly there are two types of connection.

a) Point to point connection: Provide a dedicated link between two devices the entire link is decent for transmitting between two devices.

b) Multi point connection: A multi point connection is one in which more than two specific device share a single link.

WHAT ARE THE VARIOUS TYPE OF TOPOLOGY AVAILABLE IN NETWORK.

The topology is categorise briefly in four types
1. Mesh topology,  2. Star topology,  3. Bus topology,  4. Ring topology.

MESH TOPOLOGY

In Mesh topology every device has a dedicated link to other device (point to point ). 

The term dedicated signify that, the link carries info only between the two device if connected.

ADVANTAGE:

 1. Since, Each link is dedicated, the traffic problem is less that a multi point connection.

 2. A mesh topology robust because if one link become unusable it doesn't destroy the entire network.

 3. Since, The connection is dedicated then the security problem is less.

 4. The fault identification is easier as the link is dedicated.

DISADVANTAGE:

 1. The main disadvantage of mesh is the amount of cabling and a no of I/O port required.

 2. Installation and re-installation is also difficult.

 3. The bulb of the wiring may be greater than available space.

 4. Finally the hardware requires to connect each link make the entire system expensive

 5. Hence, The mesh network is suitable to be use as a back bone of computer.

STAR TOPOLOGY:

 In STAR topology each device has a dedicated point to point link only to a central control(hub). 

The device is not directly linked to one another. 

If one device wants to send data to another it send the data to the Hub. Which is the relay of data to the other connected device.

ADVANTAGE:

 1. It is less expensive then the mesh topology.
 2. Since each device need only one link. Hence the no of cable and I/O port are less and hence it is easy to install and maintain.
 3. This topology is robust if one link failure only that machine is effected as long as the hub is working defecting link can be by passed.

DISADVANTAGE:

 1. Since each node has to be connected to the hub if the hub down the entire system collapsed.
 2. Although it require less cable then the mess topology but there are other topology which are lesser cable requirement.

 

 

BUS TOPOLOGY:

Bus topology uses a single cable which connects all the included nodes. 

The main cable acts as a spine for the entire network. 

One of the computers in the network acts as the computer server. When it has two endpoints, it is known as a linear bus topology.

A linear bus topology consists of a main run of cable with a terminator at each end (See fig. 1). 

All nodes (file server, workstations, and peripherals) are connected to the linear cable. 

ADVANTAGE:

• Easy to connect a computer or peripheral to a linear bus.
• Requires less cable length than a star topology. 
• It is simple to installed.
  

DISADVANTAGE:

• Entire network shuts down if there is a break in the main cable.
• Terminators are required at both ends of the backbone cable.
• Difficult to identify the problem if the entire network shuts down.
• Not meant to be used as a stand-alone solution in a large building. 
• limited no of taps.
  

 

 

 RING TOPOLOGY 

A ring network is a network topology in which each node connects to exactly two other nodes, forming a single continuous pathway for signals through each node – a ring.

  Data travels from node to node, with each node along the way handling every packet. 

Rings can be unidirectional, with all traffic traveling either clockwise or anticlockwise around the ring, or bidirectional

 

ADVANTAGES

• Very orderly network where every device has access to the token and the opportunity to transmit
• Performs better than a bus topology under heavy network load
• Does not require a central node to manage the connectivity between the computers
• Due to the point-to-point line configuration of devices with a device on either side (each device is connected to its immediate neighbor), it is quite easy to install and reconfigure since adding or removing a device requires moving just two connections.
• Point-to-point line configuration makes it easy to identify and isolate faults.
• Ring Protection reconfiguration for line faults of bidirectional rings can be very fast, as switching happens at a high level, and thus the traffic does not require individual rerouting

 

DISADVANTAGES

• One malfunctioning workstation can create problems for the entire network. This can be solved by using a dual ring or a switch that closes off the break.
• Moving, adding and changing the devices can affect the network
• Communication delay is directly proportional to number of nodes in the network
• Bandwidth is shared on all links between devices
• More difficult to configure than a Star: node adjunction = Ring shutdown and reconfiguration