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My boss had an interesting request.

We need a graph showing the difference between available bandwidth on an ADSL connection and a Cable connection, over time. So say, test it every 5 minutes (like Munin does!) Cable is notorious for being nice and fast at night, but not so much when the (oversubscribed) network is busy. We want to show that this is true.

Okay, I say, it shouldn't be too difficult. I just need to set up iperf and do bandwidth tests periodically, record the results, and display in Munin.

Funny thing is, that iperf is so astoundingly unstable that it can't run as a daemon for any period of time. Nevermind that after a few tries, I can't seem to get it to do it's nifty bidirectional tests (which I really need). OpenSSH is nice and stable, but scp will display the data rate of a transfer without actually, you know, being able to parse the text in any way. ftp doesn't allow transfers to be done from the unix command line, as far as I can tell.

So I need a method for measuring bandwidth from the command line, that can save the results of the data transfer rates in a text file. Any help is much appreciated.

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How do you plan on knowing whether the cable CMTS is "oversubscribed" at any given time or if it is employees saturating the line at the moment? You don't need to prove that cable can be oversubscribed "we want to show this is true"...the docsis info out there already proves that. –  TheCleaner Jul 13 '12 at 19:06
One word: Marketing. –  Ernie Jul 13 '12 at 19:13

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