Introduction to Tandem X.25 Capabilities

Multi-Vendor International Standard
What is X.25?
1–2 065307 Tandem Computers Incorporated
Figure 1-1. Proprietary Networking Conventions
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Recognizing the need for a standard, the CCITT (International Telegraph and
Telephone Consultative Committee) developed the X.25 recommendation as an
international data communications standard specifying how to connect user computer
systems to public data networks. Members of the CCITT, a committee operating
under the general auspices of the United Nations, include the Federal
Communications Commission (FCC), the Postal Telephone and Telegraph agencies
(PTTs) and common carriers, plus representatives of the computer and data
communications industries.
The X.25 recommendation was first published in 1976. It has been revised every 4
years, including 1980, 1984, and 1988. Although X.25 is technically a recommendation
rather than a standard prescribed by law, it is generally accepted and often referred to