Gateways and bridges

A wide variety of networks reside on the Internet, often using different hardware and running different software. Gateways and bridges enable these different networks to communicate with each other.

A bridge is a functional unit that connects two LANs that possibly use the same logical link control (LLC) procedure, such as Ethernet, but different medium access control (MAC) procedures. A gateway has a broader range than a bridge. It operates above the link layer and, when required, translates the interface and protocol used by one network into those used by another distinct network. Gateways allow data transfers across the various networks that constitute the Internet.