[BlueOnyx:06203] Re: Traffic monitoring - 95th percentile

[Dogsbody]

Hi Stephanie,

> Does anyone have a tool they use to track traffic on interfaces via snmp?
> Specifically I have a sudden need to track 95th percentile bandwidth usage
> for a new client and I'd like to be able to track it on a weekly and monthly
> manner with reports (not just graphs, though they are nice). Suggestions
> and/or recommendations are appreciated.

I use MRTG, "MRTG Total Traffic Generator" which you can grab from 
http://bjorn.swift.is/traffic/ and a calculator :-p  But then I'm old 
school.  I should probably move to something like NAGIOS or Cacti but 
don't actually know if they do 95th percentile either!

If I need to monitor one customer then I'll put them on a separate IP 
address and set iptables to report the traffic for that IP to MRTG. 
Remember that with this only be web traffic as all their mail will still 
go out through the primary IP address.

> I have done googling and mrtg plus rrd and several other tools looked
> promising but don't seem to offer the 95th percentile computation. Sigh.

Apologies if I am telling you something you already know and/or for the 
benefit of anyone else that wants to know... 95th percentile is only 
useful with a time duration attached.  That is, a monthly 95th 
percentile is different to a yearly 95th percentile etc.  Think of it 
like the load average on a machine where you get the 1 min, 5 min and 15 
min averages.

So with MRTG monitoring the traffic you can use the "MRTG Total Traffic 
Generator" to report on the traffic for whatever timescale you like and 
then multiply by 0.95.

The "MRTG Total Traffic Generator" is simple enough that you could 
probably script it too.

I hope that helps

Dan