DSL and Cable Speed - Bottom Line
Cable modem Internet services on average promise higher levels of bandwidth than DSL Internet services, and this bandwidth roughly translates to raw speed. However, while cable Internet will theoretically run faster than DSL, several technical and business reasons can reduce or even eliminate this advantage.
DSL vs Cable Raw Speed - Advantage Cable
In terms of theoretical peak performance, cable modem runs faster than DSL. Cable technology supports approximately 30 Mbps of bandwidth, whereas most forms of DSL cannot reach 10 Mbps.
One type of DSL technology, VDSL, can match cable's performance, also supporting 30 Mbps. However, Internet service providers generally do not offer VDSL, but rather the cheaper and slower ADSL or SDSL services.
DSL vs Cable - Real-World Speed
In practice, cable's speed advantage over DSL is much less than the theoretical numbers suggest. Why?
Cable modem services can slow down significantly if many people in your neighborhood access the Internet simultaenously.
Both cable modem and DSL performance vary from one minute to the next depending on the pattern of use and traffic congestion on the Internet.
DSL and cable Internet providers often implement so-called "speed caps" that limit the bandwidth of their services.
Some home networks cannot match the speed of the Internet connection, lowering your performance
See more... http://compnetworking.about.com/od/dslvscablemodem/a/speedcompare.htm
· 7 years ago