IDENTIFYING NETWORK TOPOLOGIES
A network topology is the physical layout of computers, cables, and other components on a network. There are a number of different network topologies, and 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
1) BUS TOPOLOGY
A bus topology uses one cable as a main trunk to connect all of the systems together. A bus topology is very easy to set up and 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 end of the cable length, it bounces back and returns in the direction it came from.
This is known as signal bounce. Signal bounce is a problem because if another signal is sent on the cable length at the same time, the two signals will collide and be destroyed and then must be retransmitted. For this reason, at each end of the cable, there is a terminator. The terminator is designed to absorb the signal when the signal reaches the end, preventing signal bounce. If there is no termination, the entire 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 entire network will go down.
A bus is a passive topology, which means that the workstations on the bus are not responsible for regenerating the signal as it passes by them.
Since the workstations do not play an active role, the workstations are not a requirement of a functioning bus, which means that if a workstation fails, the bus does not fail. But if there is an unterminated end in the bus, the entire network will fail.
2) STAR TOPOLOGY
In a star topology, all computers are connected through one central device known as a hub or a switch. Each workstation has a cable that goes from the network card to the hub device. One 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 entire network, as with a bus topology. Star topologies are very popular topologies in today’s networking environments.
3) MESH TOPOLOGY
A mesh topology is not very common in computer networking today. In a mesh topology, every workstation has a connection to every other component of the network.
4) RING TOPOLOGY
In a ring topology, all computers are connected via a cable that loops in a ring or circle. A ring topology is a circle that has no start and no end. Because there are no ends, terminators are not necessary in a ring topology.
Signals travel in one direction on a ring while they are passed from one computer to the next, with each computer regenerating the signal so that it may travel the distance required.
5) HYBRID TOPOLOGY
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 a 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 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.
6) WIRELESS TOPOLOGY
A wireless topology is one in which a 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 allows them to receive broadcasts and transmit requested data 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.
