Other intresting stuff on this !
http://compnetworking.about.com/library/weekly/aa111200b.htm
Speed Caps
Both cable and DSL service providers have commonly employed the
controversial practice of bandwidth caps for their home customers. Bandwidth
caps place an artificial limit on the maximum speed a customer can achieve
by monitoring their current usage and throttling network packets if
necessary. Service providers may have several motivations for imposing caps
including the following:
1. Providers concerned about the capacity limits of their network may
implement a short-term cap so that they can accomodate more customers
without causing scalability problems.
2. Providers may believe that the vast majority of customers do not actually
need any more bandwidth than that allowed under the cap.
3. Providers may want to create a fair-and-equal distribution of bandwidth
of customers rather than allow customers closer to the central office to
receive disproportionately more bandwidth.
4. Providers may be attempting to increase future profits by generating
demand for "premium" classes of service -- customers may be willing to pay
more for a higher cap or no-cap level of performance. <Time Warner come to
my mind!>
DSL Speed
DSL services typically offered today typically range in performance from 128
kbps to 1.544 Mbps. It can be difficult to pin down precise speed numbers
for DSL because of the many variations in equipment. DSL is also a
distance-sensitive technology, and that complicates the performance picture
even further. The bandwidth available to a home user, for example, depends
significantly on the length of cabling running from the home to the
provider's facilities as well as the electrical quality of that line.
LasVegas.NET is a fairly typical regional provider of DSL service [2]. It
offers three different performance packages as follows:
Package Downstream / Upstream Data Rate
Standard 512 kbps / 128 kbps
Premium 1.544 Mbps / 384 kbps
Executive 640 kbps / 640 kbps
Although it may seem limiting, asymmetric DSL services are still more
commonly used than symmetric ones. Most Net users require more bandwidth for
surfing the Web (that involves frequent loading of Web pages) than they do
for sending email or Web publishing (that involves transmitting data to
remote locations). Therefore, an ADSL user tends to spend very little of
their time limited by a 128 kbps upstream data rate. Symmetric DSL (SDSL)
service can be more appealing to business customers, however, who tend to
use a different mix of applications and need more bandwidth in both
directions.
Cable Speed
Cable service providers usually don't quote absolute performance numbers
like the DSL vendors because of the differences in dedicated versus shared
bandwidth. For example, on their home page the Road Runner cable modem
service states:
"Road Runner offers speeds up to 50 times faster than traditional dial-up
connections over its high-speed network ...Many factors can influence the
delivery of data, however, particularly once you are out on the Internet."
In "The Facts About Speed," the @Home(sm) cable modem service promises
upstream bandwidth of a meager 128 Kbps, but touts high downstream
performance -- even higher than Road Runner -- albeit with a similar caveat:
"With @Home, you'll download up to 100 times faster* than a 28.8K modem
<LOL YEAH RIGHT!
* Actual speeds will vary. Many factors affect download speeds <YEAH how
many people are using it and how is it capped!
enjoy
B.Preece
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