Measuring T1 usagewith MRTG

[vab at MIT.EDU (V. Alex Brennen)]

On Thu, 2006-08-31 at 20:24 -0400, Matt Shields wrote:
> Keep in mind this is only true if you have a Point-to-Point T1
> (1.54mbps).   

If you'd like to test the amount of bandwidth available to you,
you can do so with a program called iperf:

http://dast.nlanr.net/Projects/Iperf/

The way that iperf works is by sending a stream of packets as a
client for a set duration to another copy of iperf acting as a
server.  The program then reports statistics on the communication
effort (number and percentage of packets recieved, etc.)

By using iperf for a small number of one to five second tests 
during off hours, you should be able to get a clear idea of 
the amount of bandwith available to you.

Iperf has a buggy user interface in that it will report 
obviously erronous statistics if the command line options
are not given in iperf's desired order.  I can't remember
what that is off the top of my head.  So, you may need
to experiment a bit to find it.

Obviously, you'll want to do UDP testing since the Nagle
Algorithm may significantly effect your results.

When I worked in a NOC for a network wih a 10Gbit backbone,
I deployed iperf servers nationally and wrote scripts to 
test bandwidth every 15 minutes and analize and graph the 
results.

            - VAB

-
V. Alex Brennen                   vab at MIT.EDU
UNIX Systems Administrator
MIT Libraries       http://libraries.mit.edu/

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