Study of Different Network Topologies and Different Network Devices


EXPERIMENT-2.a

Aim: Study of following Network Topologies.
• Bus
• Ring
• Star
• Mesh
• Tree
• Hybrid

Apparatus (Software): No software or hardware needed.

Procedure: Following should be studied to understand this practical.

Types of Network Topology

Network Topology is the schematic description of a network arrangement, connecting various nodes(sender and receiver) through lines of connection.

1. BUS Topology

Bus topology is a network type in where every computer and network device is connected to single cable.










Bus topology in computer networks

Features of Bus Topology

  • It transmits data only in one direction.
  • Every device is connected to a single cable

Advantages of Bus Topology

  • It is cost effective.
  • Cable required is least compared to other network topology.
  • Used in small networks.
  • It is easy to understand.
  • Easy to expand joining two cables together.
Disadvantages of Bus Topology

  • Cables fails then whole network fails.
  • If network traffic is heavy or nodes are more the performance of the network decreases.
  • Cable has a limited length.
  • It is slower than the ring topology.
2. RING Topology

It is called ring topology because it forms a ring as each computer is connected to another computer, with the last one connected to the first. Exactly two neighbours for each device.


















Ring topology in computer networks

Features of Ring Topology

  • A number of repeaters are used and the transmission is unidirectional.
  • Date is transferred in a sequential manner that is bit by bit.

Advantages of Ring Topology

  • Transmitting network is not affected by high traffic or by adding more nodes, as only the nodes having tokens can transmit data.
  • Cheap to install and expand
Disadvantages of Ring Topology

  • Troubleshooting is difficult in ring topology.
  • Adding or deleting the computers disturbs the network activity.
  • Failure of one computer disturbs the whole network.

3. STAR Topology

In this type of topology all the computers are connected to a single hub through a cable. This hub is the central node and all others nodes are connected to the central node.















Star topology in computer networks

Features of Star Topology

  • Every node has its own dedicated connection to the hub.
  • Acts as a repeater for data flow.
  • Can be used with twisted pair, Optical Fibre or coaxial cable.
Advantages of Star Topology

  • Fast performance with few nodes and low network traffic.
  • Hub can be upgraded easily.
  • Easy to troubleshoot.
  • Easy to setup and modify.
  • Only that node is affected which has failed rest of the nodes can work smoothly.
Disadvantages of Star Topology

  • Cost of installation is high.
  • Expensive to use.
  • If the hub is affected then the whole network is stopped because all the nodes depend on the hub.
  • Performance is based on the hub that is it depends on its capacity
3. MESH Topology

It is a point-to-point connection to other nodes or devices. Traffic is carried only between two devices or nodes to which it is connected. Mesh has n (n-2)/2 physical channels to link hn devices.














Mesh topology in computer networks

Types of Mesh Topology

Partial Mesh Topology : In this topology some of the systems are connected in the same fashion as mesh topology but some devices are only connected to two or three devices.
Full Mesh Topology : Each and every nodes or devices are connected to each other.

Features of Mesh Topology
  • Fully connected.
  • Robust.
  • Not flexible.
Advantages of Mesh Topology

  • Each connection can carry its own data load.
  • It is robust.
  • Fault is diagnosed easily.
  • Provides security and privacy.
Disadvantages of Mesh Topology

  • Installation and configuration is difficult.
  • Cabling cost is more.
  • Bulk wiring is required.
5. TREE Topology

It has a root node and all other nodes are connected to it forming a hierarchy. It is also called hierarchical topology. It should at least have three levels to the hierarchy.





Tree topology in computer networks

Features of Tree Topology

  • Ideal if workstations are located in groups.
  • Used in Wide Area Network.
Advantages of Tree Topology

  • Extension of bus and star topologies.
  • Expansion of nodes is possible and easy.
  • Easily managed and maintained.
  • Error detection is easily done.
Disadvantages of Tree Topology

  • Heavily cabled.
  • Costly.
  • If more nodes are added maintenance is difficult.
  • Central hub fails, network fails.
6. HYBRID Topology

It is two different types of topologies which is a mixture of two or more topologies. For example if in an office in one department ring topology is used and in another star topology is used, connecting these topologies will result in Hybrid Topology (ring topology and star topology).

Features of Hybrid Topology

  • It is a combination of two or topologies
  • Inherits the advantages and disadvantages of the topologies included
























Hybrid topology in computer networks

Advantages of Hybrid Topology

  • Reliable as Error detecting and trouble shooting is easy.
  • Effective.
  • Scalable as size can be increased easily.
  • Flexible.
Disadvantages of Hybrid Topology

  • Complex in design.
  • Costly.

EXPERIMENT-2.b

Aim: Study of following Network Devices in Detail
• Repeater
• Hub
• Switch
• Bridge
• Router
• Gate Way
Apparatus (Software): No software or hardware needed.

Procedure: Following should be studied to understand this practical.

Repeater: Functioning at Physical Layer.A repeater is an electronic device that receives a signal and retransmits it at a higher level and/or higher power, or onto the other side of an obstruction, so that the signal can cover longer distances. Repeater have two ports ,so cannot be use to connect for more than two devices.










Hub: An Ethernet hub, active hub, network hub, repeater hub, hub or concentrator is a device for connecting multiple twisted pair or fiber optic Ethernet devices together and making them act as a single network segment. Hubs work at the physical layer (layer 1: Physical Layer) of the OSI model. The device is a form of multiport repeater. Repeater hubs also participate in collision detection, forwarding a jam signal to all ports if it detects a collision.










Switch: A network switch or switching hub is a computer networking device that connects network segments.The term commonly refers to a network bridge that processes and routes data at the data link layer (layer 2) of the OSI model. Switches that additionally process data at the network layer (layer 3 and above) are often referred to as Layer 3 switches or multilayer switches.












 
Bridge: A network bridge connects multiple network segments at the data link layer (Layer 2) of the OSI model. In Ethernet networks, the term bridge formally means a device that behaves according to the IEEE 802.1D standard. A bridge and switch are very much alike; a switch being a bridge with numerous ports. Switch or Layer 2 switch is often used interchangeably with bridge.Bridges can analyze incoming data packets to determine if the bridge is able to send the given packet to another segment of the network.










 
Router: A router is an electronic device that interconnects two or more computer networks, and selectively interchanges packets of data between them. Each data packet contains address information that a router can use to determine if the source and destination are on the same network, or if the data packet must be transferred from one network to another. Where multiple routers are used in a large collection of interconnected networks, the routers exchange information about target system addresses, so that each router can build up a table showing the preferred paths between any two systems on the interconnected networks.






Gateway: In a communications network, a network node equipped for interfacing with another network that uses different protocols.
  • A gateway may contain devices such as protocol translators, impedance matching devices, rate converters, fault isolators, or signal translators as necessary to provide system interoperability. It also requires the establishment of mutually acceptable administrative procedures between both networks.
  • A protocol translation/mapping gateway interconnects networks with different network protocol technologies by performing the required protocol conversions.


 



  • Summary
The features of the connecting devices can be explained in brief as follows:
  • Hub- Broadcasts data from one port to all other ports in the network.
  • Repeater- Regenerates the input data which is subjected to attenuation.
  • Switch- Intelligent device which sends data to particular port.
  • Bridge-Same function as switch but much more primitive and has lesser ports.
  • Router-Connects all computers from a LAN to internet using same IP.
  • Gateway-Needed when 2 different network technologies are being used. Acts as translator.


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