Gateways

• The TRANSLATOR -- allows communications between dissimilar systems or environments
• A gateway is usually a computer running gateway software connecting two different segments. For example an Intel-based PC on one segment can both communicate and share resources with a Macintosh computer or an SNA mainframe. Use gateways when different environments need to communicate. One common use for gateways is to translate between personal computers and mainframes
• GSNW is a gateway to allow Microsoft clients using SMB to connect to a NetWare server using NCP.
• Gateways work at the Application --> Transport layer
• They make communication possible between different architectures and environments
• They perform protocol AND data conversion / translation.
• they takes the data from one environment, strip it, and re-package it in the protocol stack from the destination system
• they repackage and convert data going from one environment to another so that each environment can understand the other environment's data
• gateway links two systems don't use the same
1. protocols
2. data formatting structure
3. languages
4. architecture
• they are task specific in that they are dedicated to a specific type of conversion: e.g. "Windows NT Server -> SNA Server Gateway"
• usually one computer is designated as the gateway computer. This adds a lot of traffic to that segment
• Disadvantages
• They slow things down because of the work they do
• they are expensive
• difficult to configure
• Remember, gateways can translate
• protocols e.g. IPX/SPX  --> TCP/IP
• and data (PC --> Mac)
• e-mail standards --> an e-mail gateway that translates on e-mail format into another (such as SMTP) to route across the Internet.