The principal difference between ADSL and SDSL is that the "upstream" and
"downstream" pipelines have different capacities. While SDSL supports the
same data transfer rate for sending and receiving data, the ADSL
"pipeline" for sending data is much smaller than the pipeline for receiving
data.
It is generally not a problem to surf the net using ADSL, as the only data that is
sent to the web server is a short web address (e.g. www.google.com).
When the web server responds by returning one or
more much larger files (e.g. web page, graphics, video streams), the
relatively larger pipeline used to receive data is able to handle the throughput.
Unfortunately, ADSL falls short when there is a need to send large volumes
of data to the web server. There are many new and emerging technologies that require a
much
greater capacity than ADSL is able to support. These are discussed later in this
tutorial.
