September 1, 2007 - Source: WindowsITPro
8 More Absolutely Cool, Totally Free Utilities
Here's our latest collection of dynamite freeware for your USB toolkit
PRTG Traffic Grapher
Paessler's PRTG Traffic Grapher takes much of its history from the original, open-source multirouter traffic grapher (MRTG) project, adding a considerable amount of user friendliness to the solution. In this freeware version, you can enumerate only three sensors, but given the simplicity of PRTG's setup process and the useful data it can provide, most administrators will find the tool valuable even with only three interfaces.
PRTG offers advanced capabilities that simplify the logging and graphing of performance data over time. Performance data can include bandwidth utilization, any SNMP-instrumented data, end-to-end LAN/ WAN latency monitoring, and traffic utilization per protocol type. PRTG collects the information on a set interval and logs it to its data stores so that you can easily monitor current and over-time network performance. Figure 4 shows PRTG's main screen while the tool is running and collecting data.
PRTG's sensors have varying capabilities. For example, you can use SNMP—a low-overhead solution on the monitoring station and on target devices—for lightweight WAN-bandwidth monitoring or for monitoring a number of other easily obtained SNMP counters (e.g., CPU utilization, memory utilization). However, if you need more traffic data, packet sniffing lets you log utilization data and break it down by protocol type. Outside of the bandwidth, PRTG can also collect data from any SNMP-based counter and log it over time. PRTG also supports the concept of an "aggregate sensor," which you can use to aggregate data for multiple individual sensors (e.g., measuring bandwidth utilization, but only across switch ports 2-7 instead of the entire switch).
The installation process is quick and painless. Within five minutes, you can have the application downloaded and plotting data in your network.