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.
Virtual-private networks or VPNs are public networks that function like private networks. VPNs operate by drawing on software-defined intelligence embedded at strategic points in a carrier network (such as those provided by AT&T, MCI Worldcom, or Sprint) forming part of the backbone of the Internet. In other words, VPNs use publicly shared facilities but allow for the creation of privacy over them. VPNs are usually Internet Protocol (IP)-based networks (i.e., using portions of the public Internet) that use encryption and tunnelling to achieve privacy of data. VPNs can also achieve privacy through a variety of intelligent mechanisms such as flexible routing of calls to different locations when nodes experience peak-hour traffic congestion, screening telephone numbers by location or by time of day, and automatically identifying telephone numbers. VPNs are becoming increasingly attractive to corporations, since they allow for private corporate data to be transmitted privately, while offering the cost effectiveness, network maintenance, network management, and diverse voice and data services that a large carrier network can provide.
Three kinds of VPNs currently exist: Remote Access VPNs, through which travelling corporate users can securely connect with their own corporate network; Intranet VPNs, where different branch offices can securely network with each other and connect to their corporate network; and Extranet VPNs, which extend an enterprise's corporate network to include partners, suppliers, and customers. VPNs are virtual because the network is dynamic, with connections set up and dissolved logically, as needed, over the physical infrastructure of the carrier network or Internet. There are no permanent, hard-wired, end-to-end connections in a VPN, as in a Local-Area Network (LAN) or Wide-Area Network (WAN). Instead, connections between corporate sites using a VPN are created and dissolved as needed, allowing bandwidth and other network resources to be utilized by other network users, when not in use by the corporation.