A computer network diagram is a mechanical drawing or electronically generated image that depicts the physical and logical topology of a network. Networks may be peer-to-peer and include as few as two devices, such as a couple of personal computers (PCs), that share data and resources and cover a small area. The network design diagram for such a setup would be a simple drawing or image showing the two computers and the interconnecting cable.
The elaboration of a computer network diagram typically is considered essential, particularly when numerous devices are involved and cover large areas. Engineers and administrators responsible for design, maintenance, and security can be aided by networking diagrams. If a device such as a router, switch, or hub malfunctions, problems will arise in the transmission of data across the network. These occurrences are reported to administrators who usually must locate the origin of the issue as quickly as possible. The computer network diagram can help them navigate the network while searching for the problem.
Not all administrators are physically located in close proximity to the physical networks for which they are responsible. This is why network diagrams can be essential to the performance of their duties. By using these drawings, they typically can visualize the physical and logical topology, allowing them to make vital decisions. It is common for large computer networks to be subdivided into sub-networks which are also usually diagrammed in order to narrow concentration on a specific section.
A computer network diagram that focuses on physical topology serves as a map for administrators and engineers much like a map of a city helps civil engineers. Wide-area networks (WANs) and local area networks (LANs) often are composed of many different components. In addition to network devices such as routers and switches, there may be a vast number of hubs, servers, and printers. Knowing where each of these devices is situated can help facilitate troubleshooting and decisions that must be made during required expansion of a network.
By contrast, a computer network diagram that focuses on logical topology serves as a pictorial explanation of the method by which data is transported through a network. These network diagrams may or may not depict physical topology. For example, token ring networks transmit data via the passing of a token that travels in a ring, or circle, from one device to another. This does not mean that the hardware composing a token ring network had to be physically arranged in a circular fashion. All devices could physically exist in a linear arrangement, but would still transport data in the token-ring fashion.