X.25 is an International Telecommunication Union-Telecommunication Standardization Sector (ITU-T) protocol standard for WAN communications that defines how connections between user devices and network devices are established and maintained in packet-switched networks (PSNs) across public data networks (PDNs)in older line environments (lines deployed in 1970s and 1980s).
Integrated Services Digital Network (ISDN) is comprised of digital telephony and data-transport services offered by regional telephone carriers to permit the transmission of voice, data, text, graphics, music, video, and other source material over existing telephone wires. There are two types of services associated with ISDN:
- Basic Rate Interface (BRI) service: offers two B channels and one D channel (2B+D) with B-channel service operating at 64 kbps and D-channel service operating at 16 kbps
- Primary Rate Interface (PRI) service: offers 23 B channels and 1 D channel in North America and Japan, yielding a total bit rate of 1.544 Mbps (the PRI D channel runs at 64 kbps)
ISDN PRI in Europe, Australia, and other parts of the world provides 30 B channels plus one 64-kbps D channel and a total interface rate of 2.048 Mbps. The Cisco ISDN implementation is offered on routers that support BRI or PRI interfaces.
Dial technologies encompass an array of functionality used to send data traffic on links that require a Dial in or Dial out connection from the router through a Dial network ( ISDN or POTS) to another data networking device (such as a router or modem). There are several important variants, including Dial on Demand Routing (DDR), Dial Backup, and Large Scale Dial Aggregation. This technology helps to optimize the use of dial links, minimizing costs associated with these links.
Technical Support and Documentation
Review additional information about X.25/ISDN/Dialer in the Technical Support site area.
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- Additional Digital Subscriber Line Information
- Additional Integrated Services Digital Network Information
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