- The logical topology, in contrast to the “physical”, is the way that the signals act on the network media, or the way that the data passes through the network from one device to the next without regard to the physical interconnection of the devices.
- A network’s logical topology is not necessarily the same as its physical topology.
- The logical Classification of network topologies generally follows the same classification as those in the physical classifications of network topologies but describes the path that the data takes between nodes being used as opposed to the actual physical connections between nodes.
1) Daisy Chains
Except for star-based network, the easiest way to add more computer into a network is by daisy chaining, or connecting each computer in series to the next. If a message is intended for a computer party way down the line, each system bunches it along in sequence until it reaches the destination. A daisy- chained network can take two basic forms – linear and ring.
- A linear topology puts a two-way link between one computer and the next. However, this was expensive in the early days of computing, since each computer (except for the ones at each end) required two receivers and two transmitters.
- By connecting the computers at each end, a ring topology can be formed. An advantage of the ring is that the number of transmitters and receivers can be cut in half, since a message will eventually loop all of the way around. When a node sends a message, the message is processed by each computer in the ring. If a computer is not the destination node, it will pass the message to the next node, until the message arrive at its destination. If the message is not accepted by any node on the network, it will travel around the entire ring and return to the sender. This potentially result in a dubling time for data.