Routing takes place on layer 3 (the network layer) of the OSI model. Whereas switches are store-and-forward devices that use MAC addresses, routers are store-and-forward devices that use IP addresses. Routers (and layer 3 switches, which also act as routers but lack some of the advanced functionality of routers) allow us to move data between networks. A router is responsible for maintaining tables of information about other routers on the network, and there are several different protocols available to enable a router to learn the topology of the network.
Often, the decision whether to use a hub/switch or a router is based on practical concerns. For example, in our hypothetical DEVELOPERS/ENGINEERING network, we could replace the backbone ...
