When we hear or read the word topology, we asked a question to our self that what is topology? So here is the answer. A topology or network topologies refer to the manner in which the cable is run to the individual workstation(host computer, group of the computer) or the network. It describes the actual layout of the computer network hardware. Two or more devices connect to a link, two or more links form a topology. Next, we’ll discuss topologies in networking.
There are two types of network topologies.
1)physical topology 2)Logical topology
Physical topology: The physical topology of a network refers to the configuration of cables, computers, and other peripherals.
Logical topology: The logical topology is the method used to pass information between workstations.
Table of Contents
Types of Network Topologies
Star Topology
Bus Topology
Ring Topology
Mesh Topology
Hybrid Topology
Star Topology: The star Topology uses a centralized device(hub, switch) connecting all computers with the help of a twisted pair cable. Each network device has a dedicated point-to-point link to the centralized device. There is no direct link between these computers and the computers can communicate via centralized device only. This strategy prevents troublesome collisions and keeps the lines of communication open and free of traffic. Star topology is one of the best and most used topologies in networking.
Example of Star Topology: if one computer A wants to send data to another computer B, computer A sends the data to a centralized device and this device then sends the data to computer B.
Advantages of Star Topology
Presently star topology is used.
Network management is much easier.
Ease of cabling installation.
Easy to detect faults and remove parts.
Network reliability is high.
If one computer or link fails, the entire system does not collapse. Only that link or computer is affected.
Disadvantages of Star Topology
If a centralized device is failing, the entire system collapses.
Cabling cost is more as each node is connected individually to the centralized device.
Require more cable than most topologies.
Moderately difficult to install.
Bus topology: But topology is the second type of network topologies. In a bus topology, all the workstations are connected to the same cable segment. The cable is terminated at each end. Without the terminator the electrical signal would reach the end of the copper wire and bounce back, causing errors on the network. Data travel in both directions until it is picked up by a workstation or server NIC. If the message is missed or not recognized, it reaches the end of the cabling and dissipates at the terminator. The connector is used in bus topology.
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Advantages of Bus Topology
IEEE 80.3 architecture is used in this topology.
It is relatively easy to install and use for small networks.
It requires fewer media than other topologies.
Failure of one node does not affect the network’s functioning.
Low cost.
Expansion is easier. A new node can be easily added by using a connector.
Disadvantages of Bus Topology
The entire network fails if there is a break in the main cable.
Difficult to configure
Difficult to troubleshoot because everything happens in a single media segment.
Higher network traffic slowdown the bus speed. Only one device transmits at a time, other devices wait for their turn.
Problems of collisions.
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Ring Topology: The ring topology is a circular loop of point-to-point links. Each device connects directly to the ring or indirectly through an interface device or drop cable. Unlike bus topology, it does not have terminators at the end of the cables. In this topology data moves from one node to another. Data moves in one direction only. Each workstation checks the message for a matching destination address. If the address doesn’t match the node simply regenerates the message and sends it on its way. If the address matches, the node accepts the message and sends a reply to the sender.
Advantages of Ring Topology
Ease of installation.
Low cost as only one cable is used.
A special internal feature called beaconing allows trouble workstations to identify themselves quickly.
There are no collisions.
Data packets travel at greater speed.
Disadvantages of Ring Topology
A ring network requires more physical media than a bus network.
Media failure on unidirectional or single loop causes complete network failure.
A break in a cable ring brings down the entire network.
Difficult to reconfigure ring topology.
Mesh Topology: In Mesh topology, each node is connected to every other node in the network. There are two types, full Mesh topology, and partial Mesh topology. In a full Mesh topology, all nodes(workstation or another device) are connected directly to each other. In a partial Mesh topology, some nodes are connected to all others, but some nodes are connected only to those other nodes with which they exchange the most data.
Advantages of Mesh Topology
If one link fails, the entire system continues to work.
There is no traffic congestion problem as dedicated links are being used.
Dedicated links ensure faster transmission without any delay.
Dedicated links also ensure data privacy and security.
Disadvantages of Mesh Topology
Connecting each device to every other device in the network make installation and reconfiguration difficult.
Cabling cost is high.
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Hybrid Topology: The hybrid topology is a type of topology that is composed of one or more interconnections of two or more networks that are based upon different physical topologies. When two hubs of different topologies are joined so that the devices attached to them can communicate, it is called a Star-Bus network. When two or more star topologies are linked together using a specialized hub called MAU(Multi-utilization Access Unit). It is known as star-Ring topology.
