What is the different type of networking / internetworking devices?

1. Repeater: Also known as a regenerator, it is an electronic device that operates only at physical layer. It gets the signal in the network before it becomes weak, regenerates the original bit pattern and gets the refreshed copy back in to the link.

2. Bridges: These function both in the physical and data link layers of LANs of similar type. They separate a larger network in to smaller segments. They contain logic that permit them to keep the traffic for every segment separate and thus are repeaters that relay a frame only the side of the segment having the intended recipient and control congestion.

3. Routers: They relay packets between multiple interconnected networks (i.e. LANs of dissimilar type). They operate in the physical, data link and network layers. They have software that enables them to verify which of the several possible paths the best for a particular transmission is.

4. Gateways: They relay packets between networks that have different protocols (e.g. among a LAN and a WAN). They accept a packet formatted for one protocol and change it to a packet formatted for another protocol before forwarding it. They operate in all seven layers of the OSI model.