Network Graphing

Visual representations of data can provide additional insight into the inner workings of your network. Merely knowing that one of your main feeds is peaking at 80% utilization isn’t very helpful when you don’t know how long the peak is, at what time, and when it started.

There are a number of graphing solutions available. Some of these are extremely simplistic and don’t do much, while others are overly powerful and provide almost too much. I prefer using Cacti for my graphing needs.

Cacti is a web-based graphing solution built on top of RRDtool. RRDtool is a round-robin data logging and graphing tool developed by Tobias Oetiker of MRTG fame, MRTG being one of the original graphing systems.

Chock full of features, Cacti allows data collection from almost anywhere. It supports SNMP and script-based collection by default, but additional methods can easily be added. Graphs are fully configurable and can display just about any information you want. You can combine multiple sources on a single graph, or create multiple graphs for better resolution. Devices, once added, can be arranged into a variety of hierarchies allowing multiple views for various users. Security features allow the administrator to tailor the data shown to each user.

Cacti is a wonderful tool to have and is invaluable when it comes to tracking down problems with the network. The ability to graph anything that spits out data makes it incredibly useful. For instance, you can create graphs to show you the temperature of equipment, utilization of CPUs, even the number of emails being sent per minute! The possibilities are seemingly endless.

There is a slight learning curve, however. Initial setup is pretty simple, and adding devices is straightforward. The tough part is understanding how Cacti gathers data and relates it all together. There are some really good tutorials on their documentation site that can help you through this part.

Overall, I think Cacti is one of the best graphing tools out there. The graphs come out very professional looking, and the feature set is amazing. Definitely worth looking into.