Gateways

Gateways

The term gateway is applied to any device, system, or software application that can perform the function of translating data from one format to another. The key feature of a gateway is that it converts the format of the data, not the data itself.

A router that can route data from an IPX network to an IP network is, technically, a gateway. The same can be said of a translational bridge that, as described earlier in this chapter, converts from an Ethernet network to a Token Ring network and back again.

Software gateways can be found everywhere. Many companies use an email system such as Microsoft Exchange or Novell GroupWise. These systems transmit mail internally in a certain format. When email needs to be sent across the Internet to users using a different email system, the email must be converted to another format, usually to Simple Mail Transfer Protocol (SMTP). This conversion process is performed by a software gateway.