** Reply to message from "Istvan Bereti" <[EMAIL PROTECTED]> on Fri,
19 Jan 2001 13:59:08 +0200
> I have a web server and a 256 ADSL line at home. How can I calculate the
> amount of users that my server can serv?
Not enough information. You say this is ADSL at 256 Kbit/s. The speed rating on
an ADSL line typically refers to the download speed. In the US ADSL upload
speeds are typically 90 Kbit/s regardless of download speed. The reason for the
low upload speed is because ADSL is considered a home service, not a business
class service. Most home users are downloading mp3's and surfing the web (ok, I
*know* that's a broad generalization, but you get my point) and don't require
much in the way of upstream bandwidth.
Also, are you transferring with HTTP 1.0 or 1.1? With 1.0 you need to open and
close a connection for each object (text, graphic, etc) on the page. This
increases the number of packets by (n-1) * 6 where n is equal to the total
number of objects on the page to allow for the tcp session setup and teardown
for each object. With 1.1, all objects are sent over the same tcp session. I
could also mention RST vs FIN, but I won't.
Finally, while the provider may tell you your upload speed is 90 Kbit/s (for
example), there is no guarantee on this number in most provider agreements. The
90 Kbit/s number is actually a MAXIMUM upload speed and may or may not ever be
attained depending on how oversubscribed the provider's network is.
Bottom line, any estimate of capacity on this system would be little more than
a guess.
Sorry!
John LeMay Jr.
Senior Enterprise Consultant
NJMC, LLC.
