Ccna routing and Switching Complete Study Guide

Circuit switching    When you hear the term circuit switching, think phone call. The big 

advantage is cost; most plain old telephone service (POTS) and ISDN dial-up connections 

are not flat rate, which is their advantage over dedicated lines because you pay only for 

what you use, and you pay only when the call is established. No data can transfer before an 

end-to-end connection is established. Circuit switching uses dial-up modems or ISDN and 

is used for low-bandwidth data transfers. Okay, I know what you’re thinking, “Modems? 

Did he say modems? Aren’t those found only in museums now?” After all, with all the 

wireless technologies available, who would use a modem these days? Well, some people do 

have ISDN; it’s still viable and there are a few who still use a modem now and then. And 

circuit switching can be used in some of the newer WAN technologies as well.