Using a Bus Topology
The bus topology was used in the Ethernet networks. It is simply a series of workstations or devices connected to a single cable (see Figure 13.1). Connecting workstations along a single cable is commonly referred to as daisy-chaining. This is the topology used for networks that are composed of 10BASE-2 or 10BASE-5 coaxial cabling.
The bus topology, although simple to implement, has a few problems, including the following:
The cable itself is a single point of failure for the LAN. Each end of the bus must be terminated. One broken or loose terminator can disrupt the entire LAN. Because all workstations or devices share a common cable, tracking down a node that is causing problems on the network can be very time-consuming. For example, a loose terminator or connector on a single workstation can disrupt the entire LAN, and you might spend hours going from one node to the next checking connections. Bus topologies for Ethernet are usually built using coaxial cable (10BASE-2 and 10BASE-5). Although less cable is used than in a star topology, these cables are more expensive than simple twisted-pair cables. In the case of 10BASE-5, the cable is not very flexible and can be difficult to route through wall or ceiling structures.
In spite of its limitations when used to connect individual workstations into a LAN, the bus is a method that has often been used to join smaller groups that are connected in star formation. For example, before Fast Ethernet and Gigabit Ethernet using fiber-optic cables were developed, connections between hubs or switches in a LAN were often done using coaxial cable.
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