Gateways¶

A gateway is a computer which is able to couple completely different networks. Gateways are operating on a layer above layer 3 of the ISO/OSI model. They are used to convert different protocols to each other. For the connected subnetworks, a gateway is a directly addressable computer (node) with the following tasks:

Address and format transformation
Conversions
Flow control
Necessary adaptations of transmission rates for the transition to the other subnetworks.

Gateways can furthermore be used to implement safety functions on the application layer (firewalls). For example, gateways are used for the coupling of PCs located in local area networks (LAN) to public long distance communications (wide area networks, WAN).