Topology
The term Network Topology in computer network refers to the means a network is set out, either physically or logically.
Two or a lot of network devices are connected with 2 or a lot of links type a topology. The Topology is the geometric illustration of the link of all the links and linking devices usually known as nodes to every difference.
Network topology defines the physical or logical arrangement of links in an exceedingly network.
These are 5 labels describe however the devices in an exceedingly network square measure interconnected instead of their physical arrangement.
Example:- having a topology doesn’t mean that every one of the computers within the network should be placed physically around a hub in an exceeding star form.
A thought once selecting a topology is that the relative standing of the devices to be coupled. 2 relationships square measure possible: peer-to-peer, wherever the devices share the connect equally, and primary-secondary, wherever one device controls traffic and also the others should transmit through it.
Ring and mesh topologies square measure a lot of convenience for peer-to-peer transmission, whereas star and tree square measure a lot of convenience for primary-secondary.
Types of Network Topology
- Mesh Topology
- Star Topology
- Tree Topology
- Bus Topology
- Ring Topology
- Hybrid topology
Mesh Topology:-
In a Mesh network topology, each device contains a dedicated point-to-point link to each different device.
The term dedicated implies that the link carries traffic solely between the 2 devices it connects.
A completely connected mesh network thus has n(n – 1)/2 physical channels to link n devices. To accommodate several links, each device on the internetwork should have n-1 input/output (I/O) ports.
A mesh offers many blessings over different network topologies.
- The utilization of dedicated links guarantees that every association will carry its own information load, so eliminating the traffic issues that may occur once links should be shared by multiple devices.
- The network topology in computer networks is strong. If one link becomes unusable, it doesn’t incapacitate the complete system.
Advantages of Mesh topology:-
- The advantage is privacy or security. once each message sent travels on a frenzied line, solely the meant recipient sees it. Physical boundaries forestall different users from gaining access to messages.
- Finally, point-to-point links build fault identification and fault isolation straightforwardly. Traffic is often routed to avoid links with suspected issues.
- This facility permits the internetwork manager to get the precise location of the fault and aids to find its cause and resolution
Disadvantages of Mesh topology:-
- The main disadvantages of a mesh area unit are associated with the number of cabling and also the number of I/O ports needed.
- each device should be connected to each different device, installation, and reconfiguration area unit tough.
- Second, the sheer bulk of the wiring is often bigger than the on-the-market area (in walls, ceilings, or floors) will accommodate.
- And, finally, the hardware needed to attach every link (I/O ports and cable) are often prohibitively high-priced.
For these reasons, network topology in the computer networks is typically enforced in a very restricted fashion for example, as a backbone connecting most computers of a hybrid network that may embody many different Topologies.
Star Topology:-
In star topology, each device features a dedicated point-to-point link only to a central controller, usually called a hub. The devices aren’t directly linked to every other.
Unlike a mesh, a star doesn’t allow direct traffic between devices The controller acts as an exchange: If one device wants to send data to a different, it sends the info to the controller, which then relays the info to the opposite connected device.
A star is a smaller amount expensive than a mesh. In a star, each device needs just one link and one I/O port to attach it to any number of others.
This factor also makes it easy to put in and reconfigure. Far less cabling must be housed, and additions, moves, and deletions involve just one connection between that device and therefore the hub.
Advantages of star topology:-
- The other advantages include robustness. If a single link fails, only that link is affected. All other links remain active.
- This factor also lends itself to simple fault identification and fault isolation As long as the hub is functioning, it is often wont to monitor link problems and bypass defective links
- However, although a star requires far less cable than a mesh, each node must be connected to a central hub. For this reason, more cabling is required during a star than in other topologies (such as tree ring. or bus).
Tree Topology:-
A tree topology may be a variation of a star. During a star, nodes during a tree are linked to a central hub that controls the traffic to the network.
However, not all device plugs directly into the central hub. The majority of devices are connected to a secondary hub that successively is connected to the central hub.
The central hub within the tree is a lively hub. An active hub contains a repeater, which may be a hardware device that regenerates the received bit patterns before sending them out. Repeating strengthens transmissions and increases the space a sign can travel.
The secondary hubs could also be active or passive hubs. A passive hub provides an easy physical connection between the attached devices.
Advantages and disadvantages of tree topology:-
- The advantages and drawbacks of a tree Network topology in a computer network are generally equivalent to those of a star.
- It allows more devices to be attached to one central hub and may, therefore, increase the space a sign can travel between devices.
- It allows the network topology in computer networks to isolate and prioritize communications from different computers.
For example, the computers attached to at least one secondary hub are often given priority over computers attached to a different secondary hub.
In this way, the network designers and operators can guarantee that time-sensitive data won’t need to await access to the network.
A good example of a tree topology is often seen in cable television technology where the most cable from the post office is split into main branches and every branch is divided into smaller branches and so on. The hubs are used when a cable is split.
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Bus Topology:-
The preceding examples all describe point-to-point configurations. A bus, on the opposite hand, is multipoint. One long cable acts as a backbone to link all the devices within the network topology in a computer network.
Nodes are linked to the bus cable by drop lines and taps. A drop line may be a connection running between the device and therefore the main cable.
A tap may be a connector that either splices into the most cable or punctures the sheathing of a cable to make a contact with the metallic core. As a sign travels along the backbone, a number of its energy is transformed into heat.
Therefore, it becomes weaker and weaker the farther it’s to travel For this reason there’s a limit on the number of taps a bus can support, and on the distance between those taps.
Advantages of bus topology:-
- The advantages of a bus include simple installation. Backbone cables are often laid along the foremost efficient path, then linked to the nodes by drop lines of varying lengths. This means a bus uses less cabling than mesh, star, or tree topologies. In a star,
For example, four network devices within the same room require four lengths of cable reaching all the thanks to the hub.
On a bus, this redundancy is eliminated. Only the backbone cable stretches through the whole facility: Each drop line has got to reach only as far because of the nearest point on the backbone.
disadvantages of bus topology:-
- Disadvantages include difficult reconfiguration and fault isolation. A bus is typically designed to be optimally efficient at installation. It can, therefore, be difficult to feature new devices. As mentioned higher than, signal reflection at the tap will cause degradation in quality.
- This degradation is often controlled by limiting the amount and spacing of devices connected to a given length of cable. Adding new devices might, therefore, need modification or replacement of the backbone.
In addition, a fault or break within the bus cable stops all transmission, even between devices on an equivalent side of the matter. The damaged area reflects signals back within the direction of origin, creating noise in both directions.
Ring Topology:-
In a Ring topology, each device features a dedicated point-to-point line configuration only with the 2 devices on either side of it. a sign is passed on the ring in one direction, from device to device, till it reaches its destination.
Every device within the ring incorporates a repeater. When a tool receives a sign intended for an additional device, its repeater regenerates the bits and passes them along.
A ring is comparatively easy to put in and reconfigure. Each device is connected only to its immediate neighbors (either physically or logically).
To add or delete a tool requires moving only two connections. The only constraints are unit media and traffic concerns (maximum ring length and range of devices). In addition, fault isolation is simplified.
Generally, during a ring, a sign is circulating at the least times. If one device doesn’t receive a sign within a specified period, it can issue an alarm. The alarm alerts the network operator to the matter and its location.
However, unidirectional traffic is often an obstacle during a simple ring, an opportunity within the ring (such as a disabled station) can disable the whole network. This weakness is often solved by employing a dual ring or a switch capable of isolating the break.
Hybrid Topologies:-
Often a network combines several topologies as subnetworks linked together during a larger topology. For instance, one department of a business may have decided to use a bus topology while another department features a ring.
The two are often connected to every other via a central controller during a star.
Conclusion:-
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