Wide-Area Network and Dialup Network Technologies

Cisco devices support a large number of WAN and dialup technologies. We cover the most popular of these technologies in this chapter:

  • High-Level Data Link Control (HDLC)

  • Point-to-Point Protocol (PPP)

  • X.25

  • Frame Relay

  • Asynchronous Transfer Mode (ATM)

  • Digital Subscriber Line (DSL)

  • Integrated Services Digital Network (ISDN)

Like the LAN protocols we have considered in this chapter, these WAN protocols operate at the data link layer of the OSI reference model. The WAN protocols transfer data across an asynchronous or synchronous serial interface from one location to another.


Synchronous serial transmissions are digital signals that are transmitted with precise clocking from one device to another. ...

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