Devices needed for internetworking. Types are:

- Router: A router connects two or more networks with all networks following the same set of protocols. As data are passed through a router, it determines the best transmission route for these data and sends them on it. Data travel from router to router until they reach a router that attaches directly to the network of the destination computer. Thus, the router system forms the architectural basis of an internet and handles all traffic except for direct delivery from one computer to another.

- Gateway: It is a router connecting two or more networks that do not follow the same set of protocols. Thus, it performs the additional task of protocol mapping.