Topology refers to the pattern in which network devices or nodes are connected. Some common topologies include:
In a bus topology, each node is connected to the same shared medium. For example, a cable could be run from end to end in a building, and each device could connect to it.
In a ring topology, each device is connected to two neighbors. The first device in the ring is also the last device, so the network forms a complete logical circle.
In a star topology, each device connects to one central device (typically, a router, switch, or hub). In an extended star topology, the devices that stand at the center of their own stars are themselves connected to another central device, forming a star of stars. A multilayered extended star topology takes the form of a logical tree.
In a mesh topology, each device is connected to several other devices. In a full mesh, each device connects directly to each of the others. In a partial mesh, some devices do not connect directly to all the others, yet the pattern of connections is still more complex than a bus, a ring, or a star.