On 14-May-07 14:03:51, Tim Green wrote:
On 5/14/07, Ted Harding ted.harding@nessie.mcc.ac.uk wrote:
I do not trust any of the on-line speed-checkers. In the days when I was systematically checking my own ADSL speeds, I would download (ftp) a 4.5MB file from my account on a remote host at Manchester (not 100 miles from my ISP, Zen, at Rochdale).
I consistently got at least twice the transfer speed that I got from any speed-checker. (It was a ".doc" Word file that someone once emailed me, so a close approximation to random bytes and not likely to benefit much from in-line compression, if any).
Have you tried compressing the Word file? I think you'll be surprised.
It's already 'gzip -9'd (sorry, I should have said that).
Are you saying your transfer speed was twice the expected speed, or the on-line speed-checker was half the expected speed?
The file size divided by the transfer time in Kbits/sec (as reported when ftp completes) is typically about half the reported speed from on-line speed-checkers (or less). Note that I'm not counting "packet overheads" here: it's bytes of file content. If I added in the overheads, it would be faster still!
Ted.
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