[Semibug] Diagnosing a saturated network.

Mike Wayne semibug15 at wayne47.com
Wed Jan 11 13:00:21 EST 2017

On Wed, Jan 11, 2017 at 12:07:25PM -0500, Jeremy Gransden wrote:
> I have a network of 8 pcs and several phones all connected to the
> Internet and our other locations via a single T1 line. 

Not sure of your options here but consider dropping in a broadband
(cable?) connection at each location and creating VPNs between
them all. You'll keep security, possibly save money and get
more bandwidth. Plus each location gets fast general Internet.
Assuming you are running VOIP phones, this should all work fine.

> How would i find out what host is using the most bandwidth at the
> FreeBSD bridge?

For monitoring, I would start by installing mrtg and configure it
to watch the traffic on each switch port as well as the T1. That'll
get you started and give you a better idea of what bandwidth looks
like on your network. 

Then, you can install nagios to watch the mrtg data and bitch when 
traffic exceeds certain levels. Note that you can do all sorts of 
creative things here like:
   (T1 bandwidth > 1,400,000 bps) && (switch port > 750,000 bps)	[T1 is 90% used and user is using > 50% of max bandwidth]

More involved: write dummynet rules to limit bandwidth to each IP
address which would automatically deal with the problem. Dummynet
would also permit you to monitor traffic to IP address, port, etc.

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