BUS TOPOLOGIES AND THEIR ADVANTAGES AND DISADVANTAGES
A bus topology uses one cable as a main trunk to connect all of the systems together (shown in Figure.1). 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 re-transmitted. 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, as shown in Figure 2.
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.
|Figure 2: A break in the cable with the bus topology|
- Simple and easy to install: Bus topology is simple to install and does not require complex wiring or cabling.
- Cost-effective: Bus topology is relatively inexpensive compared to other network topologies.
- Easy to expand: New devices can be easily added to the network by simply connecting them to the bus.
- Single point of failure: If the main bus cable is damaged, the entire network will fail, making it a single point of failure.
- Limited cable length: The length of the bus cable is limited, so the number of devices that can be connected is also limited.
- Performance degradation: As more devices are added to the network, performance may degrade due to increased traffic and collision on the bus.
- Difficult to troubleshoot: Diagnosing and fixing problems in a bus topology can be difficult as all devices are connected to the same cable.
- Not suitable for large networks: Bus topology is not suitable for large networks as it does not provide the scalability and performance required for large networks.