What kind of performance are you seeing with your new
modem? Email us the results and we'll post them to a reader
survey page. Naturally, we assume that your ISP is also
using V.90 modems.
Testing modem performance is a bit of a black art. Here
are some tips for getting meaningful, reproducible results.
FILE SIZE
Size wise, download a file of at least 200 kilobytes to
minimize the effects of latency and TCP/IP slow start.
DOWNLOAD PRE-COMPRESSED FILES
For consistency's sake, download a file that's
pre-compressed with an efficient software utility, such
as WinZip for Windows (.zip files) or StuffIt for
Macintosh (.sit files). If you download an uncompressed
file, your modem's hardware data compression protocols
(such as MNP 5 and V.42bis), will compress the file,
leading to higher transfer rates. That's good for
performance, but bad for testing purposes. Different
kinds of files compress to different degrees, making it
impossible to compare the results of different downloads
and different modems.
DOWNLOAD LOCALLY
For testing purposes, you should download the file from
your ISP's computers. When you download a file from
across the Internet, you're adding extra variables, such
as congestion between the ISP and the rest of the
Internet. Remember: you want to test your modem, not your
ISP's connectivity to the Internet. Your ISP probably has
an FTP site you can download files from.
USE FTP - NEVER A WEB BROWSER
You should also use an efficient downloading program,
such as an FTP program, or a plain old terminal program
that supports Zmodem. Web browsers are absolutely
terrible for measuring performance. The HTTP protocol is
inefficient, and the browser has to download information,
write it do a disk cache, and format the information for
the screen. How inefficient is the HTTP 1.0 protocol? To
download a web page with a block of text and ten unique
pictures, the web browser must open and close 11 separate
connections to the web server.
Is it OK to use a web browser for performance testing
if you're doing an FTP download? Unfortunately, no,
because Netscape and Microsoft's browsers sometimes
report inaccurate download rates. A long download can
pause for seconds or even minutes without affecting the
reported download rate. Stick with an FTP program. Most
FTP programs report accurate download rates, and display
the transfer rate when the download is complete. You can
download WS_FTP and Cute FTP for Windows from Strouds, or
Anarachie and Fetch for Macintosh from The Mac Orchard.
Post your results to the V.90
Survey message board.
