Network Topologies

A network topology is the physical layout of computers, cables, & other parts on a network. There's a considerable number of different network topologies, & a network may be built using multiple topologies. The different types of network layouts are

• Bus topology
• Star topology
• Mesh topology
• Ring topology
• Hybrid topology
• Wireless topology

Bus topology

A bus topology makes use of cable as a main trunk to connect all of the systems together . A bus topology is very simple to set up & requires no additional hardware such as a hub. The cable is also called a trunk, a backbone, or a segment.

With a bus topology, when a computer sends out a signal, the signal travels the cable length in both directions from the sending computer. When the signal reaches the finish of the cable length, it bounces back and returns in the direction it came from. This is named signal bounce. Signal bounce is a controversy, because if another signal is sent on the cable length simultaneously, the signals will collide and be destroyed and then must be retransmitted. For this reason, at each finish of the cable there is a terminator. The terminator is designed to absorb the signal when the signal reaches the finish, stopping signal bounce. If there is no termination, the whole network fails because of signal bounce, which also means that if there is ever a break in the cable, you will have unterminated ends and the whole network will go down.

Advantages of a Bus Topology

One advantage of a bus topology is cost. A bus topology makes use of less cable than a star topology or a mesh topology, & you do not need to buy any additional devices such as hubs. Another advantage of a bus topology is the ease of installation. With a bus topology, you connect the workstation to the cable segment or backbone. You need only the amount of cable to connect the workstation to the backbone. The most economical choice for a network topology is a bus topology, because it is simple to work with & a minimal amount of additional devices are necessary. Most importantly, if a computer fails, the network stays functional.

Disadvantages of a Bus Topology

The main disadvantage of a bus topology is the difficulty of troubleshooting it. When the network goes down, it is usually due to a break in the cable segment. With a immense network, this issue can be hard to isolate.Scalability is an important consideration in the dynamic world of networking. Being able to make changes basically within the size & layout of your network can be important in future productivity or downtime. The bus topology is not very scalable

Star topology

In a star topology, all computers are connected through central tool known as a hub or a switch, as illustrated. Each workstation has a cable that goes from the network card to the hub tool. of the major benefits of a star topology is that a break in the cable causes only the workstation that is connected to the cable to go down, not the whole network, as with a bus topology. Star topologies are popular topologies in today's networking environments.

Advantages of a Star Topology

One advantage of a star topology is scalability & ease of adding another process to the network. In the event you need to add another workstation to the network with a star topology, you connect that process to an unused port on the hub. Another benefit is the fact that if there is a break in the cable it affects only the process that is connected to that cable. Centralizing network parts can make an administrator life much simpler in the long run. Centralized management & monitoring of network traffic can be vital to network success. With a star configuration, it is also simple to add or change configurations because all of the connections come to a central point.

Disadvantages of a Star Topology

On the flip side, if the hub fails in a star topology, the whole network comes down, so they still have a central  point of failure. But this is a much simpler issue to troubleshoot than trying to discover a cable break with a bus topology. Another disadvantage of a star topology is cost. To connect each workstation to the network, you will need to be definite that there is a hub with an obtainable port, and you will need to be definite you have a cable to go from the workstation to the hub. Today, the cost is increasingly less of a disadvantage because of the low prices of devices such as hubs and switches.

Mesh topology

A mesh topology is not common in computer networking today, but you must understand the idea for the examination. In a mesh topology, every workstation has a connection to every other part of the network, as illustrated

Advantages of a Mesh Topology

The largest advantage of a mesh topology is fault tolerance, meaning that, if there is a break in a cable segment, traffic can be rerouted through a different pathway because there's multiple pathways to send information from technique to another. This fault tolerance means that it is  impossible for the network to go down due to a cable fault.

Disadvantages of a Mesh Topology

A disadvantage of a mesh topology is the cost of the additional cabling and network interfaces to generate the multiple pathways between each method. A mesh  Topology is very hard to administer and manage because of the numerous connections.

Ring topology

In a ring topology, all computers are connected by a cable that loops in a ring or circle. As shown in a ring topology is a circle that has no start & no end. Because there's no ends, terminators are not necessary in a ring topology.Signals travel in direction on a ring while they are passed from computer to the next, with each computer regenerating the signal so that it may travel the distance necessary.

Advantages of a Ring Topology

A major advantage of a ring topology is that signal degeneration is low because each workstation is responsible for regenerating or boosting the signal. With the other topologies, as the signal travels the wire, it gets weaker & weaker due to outside interference: finally, it becomes unreadable if the location technique is faraway. Because each workstation in a ring topology regenerates the signal, the signal is stronger when it reaches its location & seldom needs to be retransmitted.

Disadvantages of a Ring Topology

The largest issue with ring topologies is that if computer fails or the cable link is broken, the whole network could go down. With newer know-how, however, this isn't always the case. The idea of a ring topology today is that the ring won't be broken when a technique is disconnected; only that technique is dropped from the ring.Isolating a controversy can be difficult in some ring configurations. (With newer technologies, a workstation or server will put out a beacon if it notices a break in the ring.) Another disadvantage is that in the event you make a cabling change to the network or move a workstation, the brief disconnection can interrupt or bring down the entire network.

Hybrid topology

It is important to note that it is typical for networks to implement a mixture of topologies to form a hybrid topology. For example, a very popular hybrid topology is a star-bus topology, in which a number of star topologies are connected by a central bus,  This is a popular topology because the bus will connect hubs that are spread over distance. Another very popular hybrid topology is the star-ring topology. The star-ring topology is popular because it looks like a star but acts as a ring. For example, there is a network architecture known as Token Ring (more on this later, in the section Network Architectures) that uses a central hub type device, but the internal wiring makes a ring. Physically it looks like a star, but logically it acts as a ring topology.

Wireless topology

A wireless topology is in which few cables are used to connect systems. The network is made up of transmitters that broadcast the packets using radio frequencies. The network contains special transmitters called cells, or wireless access points, which extend a radio sphere in the shape of a bubble around the transmitter.This bubble can extend to multiple rooms and possibly floors in a building. The PCs and network devices have a special transmitter-receiver, which lets them get broadcasts and transmit requested information back to the access point. The access point is connected to the physical network by a cable, which allows it, and any wireless clients, to communicate with systems on the wired network. A wireless network topology is the wireless cells, or access points, are connected to the network by connecting in to the hub or switch that has a connection to the remainder of the wired network. Also notice that the clients do not have cables connecting them to the network. These are wireless clients, and they will get access to the network through the wireless cell (or access point). An other option for wireless networks is the use of a radio antenna on or near the building, which allows cell to cover the building and the surrounding area. This approach is best in a campus-type arrangement, where lots of buildings that need to be included in the cell are in a close geographical area. This setup does not easily

Advantages of a Wireless Topology

The nice thing about wireless networks is the lack of cabling. The wireless network requires only base backbone segments to connect the wireless cells to the wired network if there is one. Once these are set up, the PC and network devices also need the special transmitter-receiver network interface cards to allow the PCs and devices to communicate with the cell and then through the cell to the servers. Troubleshooting failed devices and cells is very easy and makes failed components easy to find and replace.

Disadvantages of a Wireless Topology

Disadvantages of wireless networks include a greater chance of signal interference, blockage, and interception. Other devices and machinery that emit radio frequencies or “noise” can cause interference and static, which can disrupt the bubble of communication around the cell. Another source of noise is lightning during storms. This noise is the same static you hear when lightning strikes while you are speaking on a phone. Blockage can occur in structures that are made of thick stone or metal, which do not allow radio frequencies to pass through easily. This drawback usually can be overcome somewhat by changing the frequency used by the devices to a higher frequency. You can determine early if this is going to be a problem in your building by trying to use a radio inside the building to pick up some radio stations. If the radio will not pick them up, the building material is too thick to allow radio frequencies to pass through the walls. This problem can be overcome by installing a cell in each room where a PC or network device will be placed.
Another major disadvantage with wireless is signal interception. Signal interception means unwanted third parties could intercept wireless communications without physically being on the premises; they would simply have to be within the signal range. One of the key steps to securing wireless communication is to limit who can connect to the network and to encrypt the traffic in transit.