MRTG is an acronym for Multi Router Traffic Grapher and is a free, open-source tool to monitor the traffic load (data sent and received) on network links.

MRTG generates HTML (web) pages containing graphical images, which provide a live visual representation of this traffic.

How does this affect me?

If you're hosting a colocated server with JustNet or GoWeb, we provide access to mrtg stats to help you monitor your server traffic.

This helps you view trends over time and notice any unusual network activity (such large spikes of traffic, or traffic that is lower than normal). MRTG graphs are also provided for dedicated server clients, for much the same reasons.

An example mrtg graph

Here is an example of what an mrtg graph looks like:

The blue represents outbound traffic (data sent) and the green represents inbound traffic (data received). For most web servers there will be more outbound traffic (blue) than inbound traffic (green), as illustrated in the example above.

Reading such a graph is very simple. The x-axis of the graph (along the bottom) is a measurement of time depicted in hourly blocks (marked every 2 hours) and updated every 5 minutes. In this example, the graph "grows" to the right, in the direction of the red arrow in the bottom right hand corner. This means new data appears on the graph on the right-hand side, and older data "drops off" the left hand side. The red vertical line is midnight (hour = 0), and the current time in this graph is after 6 a.m. but not yet at 8 a.m., probably something like 7.30 a.m.

The y-axis (along the left) is a measurement of bandwidth (amount of traffic/data being sent or received per second at a particular time). This is shown in bits per second, and varies depending on the amount of traffic sent: higher spikes mean more traffic.

An mrtg graph with higher traffic volume

Compare a second example (below) with the first (above) and you will see that the units to measure bandwidth adjust to the maximum amount of traffic used, while the measurement of time has stayed the same.

Further information about mrtg

MRTG's homepage has further details on the software, as well as links to the many and varied uses to which mrtg has been put (such as plotting temperature, power consumption and even tidal movements).

Last updated 07 Apr 2005

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