The following sections of this BookRags Literature Study Guide is offprint from Gale's For Students Series: Presenting Analysis, Context, and Criticism on Commonly Studied Works: Introduction, Author Biography, Plot Summary, Characters, Themes, Style, Historical Context, Critical Overview, Criticism and Critical Essays, Media Adaptations, Topics for Further Study, Compare & Contrast, What Do I Read Next?, For Further Study, and Sources.
(c)1998-2002; (c)2002 by Gale. Gale is an imprint of The Gale Group, Inc., a division of Thomson Learning, Inc. Gale and Design and Thomson Learning are trademarks used herein under license.
The following sections, if they exist, are offprint from Beacham's Encyclopedia of Popular Fiction: "Social Concerns", "Thematic Overview", "Techniques", "Literary Precedents", "Key Questions", "Related Titles", "Adaptations", "Related Web Sites". (c)1994-2005, by Walton Beacham.
The following sections, if they exist, are offprint from Beacham's Guide to Literature for Young Adults: "About the Author", "Overview", "Setting", "Literary Qualities", "Social Sensitivity", "Topics for Discussion", "Ideas for Reports and Papers". (c)1994-2005, by Walton Beacham.
All other sections in this Literature Study Guide are owned and copyrighted by BookRags, Inc.
A gateway is a machine that connects different types of networks to form an internetwork using various communications protocols (rules for exchanging messages). A gateway allows information to be passed between a sending network and a receiving network. Without a gateway, different types of network are in general incompatible and thus unable to communicate with each other. The gateway itself is a combination of hardware and software. It may contain devices such as protocol translators, impedance matching devices, rate converters, fault isolators, and signal translators.
A gateway accepts information from whichever network is sending at the moment and reformats it to be compatible with the protocols used by the receiving network. It performs complete conversions from one protocol to another rather than simply supporting one protocol from within another. For example, a gateway can convert a Transmission Control Protocol/Internet Protocol (TCP/IP) packet (a collection of bits organized into a self-contained message like a piece of mail) to a Novell NetWare Internetwork Packet Exchange (IPX) packet and vice versa, or from AppleTalk (an Apple Computer local area network protocol) to DECnet (a network protocol created by Digital Equipment Corporation) and vice versa--to name few possible protocol conversions. Most commercial online services operate a gateway that translates between their internal, proprietary electronic-mail (e-mail) format and the Internet e-mail format. Gateways between e-mail systems allow users on different e-mail systems to exchange messages between messaging protocols. This specific type of support gateway is called a messaging gateway.
For example, a Cisco 3640 router acts as a gateway between the Internet service provider Cyberstation and the telecommunications company MCI, Inc. The gateway routes traffic bound for the Internet out to its destination, while keeping traffic meant for end-points within the Cyberstation constellation of users on the Cyberstation side of the gateway. It also keeps information meant to remain within MCI on MCI's side of the router.
Gateways are also referred to as routers and as protocol converters. A protocol converter is especially any device or program that translates between different protocols that serve similar functions, for instance TCP (Transmission Control Protocol, the most common transport-layer protocol on the Internet) and TP4 (Transport Protocol 4). A router (also sometimes called a gateway) is a device that forwards packets between two broadcast networks.