Shunra's Storm

If you're looking for a hardware-based network modeling tool that does a great job on the WAN, check out Shunra's Storm.

Shunra's approach to network modeling is empirical - it literally records the network conditions directly and plays them back, while enabling actual applications to run against the recorded model. Because of this approach, some typical modeling parameters don't apply to the product, such as importing network configurations from CiscoWorks or OpenView.

Configuration involved right-clicking on a link or device in Visio, and making the desired changes through a drop-down menu. We could then observe the changes on the network by watching how the applications running through the StormAppliance behaved. A built-in Sniffer-like protocol decodes function was an appreciated plus. Shunra's reporting function produces a very nice real-time chart that displays throughput per second in and out, queues, delay, and packet counts.

Shunra is a hardware-based network modeling product. That gives it somewhat of an edge in terms of performance over an entirely software based modeling application. In most instances its speed was as good or better than the other products in terms of implementing network modeling changes. However the appliance did have an annoying tendency. Whenever we changed certain model parameters, we had to warm boot the hardware. For example, switching the StormAppliance between Layer 2 and Layer 3 (switching and routing) required a reboot, as did turning on and off multicast. The reboot process was slow, taking more than two minutes.

The Shunra/Storm STX package included the StormAppliance hardware, StormCatcher (enables the capture and replay of network activity) and StormConsole. The StormAppliance is responsible for emulating link conditions such as bandwidth, packet loss, delay, and out-of-order packets. The StormConsole (a Microsoft Visio macro) creates the network model and is used as the interface to the StormAppliance. Installation of StormCatcher and StormConsole was brief. We had some problems attaching our laptop to the network ports on the StormAppliance.

Shunra provided a professionally printed user manual. The configuration procedure is nicely laid out.

While Shunra doesn't compare to some other vendors when it comes to in-depth enterprise network modeling, it does can show how applications and networks can be affected by bandwidth throttling, link limitations, packet delay, jitter, etc. Using Visio as the device interface was a brilliant idea. It is the rare network engineer or designer who isn't at least somewhat familiar with Visio. This makes it a terrific front end to Shunra Storm STX, and significantly reduces the learning curve. It has excellent capabilities to simulate frame relay, T-1s, and Gigabit links. This coupled with drop downs that allow on-the-fly changes to links, make Shunra Storm STX a natural for modeling WAN connections.

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