Could any port be sucking up bandwidth?

David Brodbeck gull at
Fri Jan 28 22:45:10 UTC 2011

On Tue, Jan 25, 2011 at 10:49 PM, Gary Kline <kline at> wrote:
> Before the 11th of January I was streaming both audio and video
> streams with little to zero wait time.  In other words, I could
> stream about 50 minutes of audio with only a second or two of pause
> time delay [[AKA congestion]].  After that date there was a steep
> decline in streaming performance and I went at upgrading my server
> with a vengeance to see if that fixed things.  Upgrading my 700
> ports only led to other things breaking.  I am wondering if anyone
> else in North America has a DSL connection and has seen the kind of
> degradation in performance after doing (something) to their FreeBSD
> servers.
> I have around 1Mb down and 864Kb up ... according to the telco.
> Any ideas will be much appreciated.

iftop will tell you how much bandwidth you're actually consuming, to
what hosts, and on what ports.  This may help you narrow down the
problem, if there is in fact something using it up.

You may want to try one of the "internet speed test" sites (e.g., to see if you're actually getting the bandwidth you
think you should be getting.  I had a similar problem and quickly
found my DSL upstream bandwidth had dropped by a third.  After some
calls to the service provider I was able to get it resolved.

You may also want to see if your streaming video site changed
something.  The trend is to upgrade to higher-bandwidth streams for
the benefit of people who have fast cable modem connections, but it
can lead to a lot of buffering delays for us DSL customers.

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