In this chapter, you learned the difference between the following WAN services: cable, DSL, HDLC, PPP, PPPoE, and Frame Relay. You also learned that you can use a VPN once any of those services are up and running.
I have to tell you—you must understand High-Level Data-Link Control (HDLC) and how to verify with the show interface command that HDLC is enabled! You’ve been provided with some really important HDLC information as well as information on how the Point-to-Point Protocol (PPP) is used if you need more features than HDLC offers or if you’re using two different brands of routers. You now know that this is because various versions of HDLC are proprietary and won’t work between two different vendors’ routers.
When we went through ...