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Product Reviews
March 2003

Shunra\Cloud 4.0


Shunra Software Ltd.

555 Eighth Ave., Ste. 1102

New York, NY 10018

Tel: 877-474-8672

Web site: www.shunra.com

Price: $5,900

Editor's Choice Award

Installation: 4.75
Documentation: 4.25
Features: 5
GUI: 5
Overall: A-

Testing the performance of network applications, such as a CRM application or a latency-sensitive application, such as VoIP, can be quite tricky. Developers often test their applications on a clean high-speed test network in a lab environment as opposed to a �real world� network. As such, issues such as bandwidth bottlenecks, jitter, latency, packet loss, etc., are non-factors on a clean testing network.

Shunra Software helps solve this problem with their software-based network emulation tool called Shunra\Cloud v4.0 that will help developers understand how their applications will work in a real-world scenario before they are deployed. In addition, network managers will love this software tool to see how much impact a set amount of latency or packet loss can affect specific applications already deployed on the network. Shunra\Cloud tests are fully customizable, repeatable, and can be automated, enabling users to perform �what if� scenarios and determine the real end-user experience, without the risk of testing over the real network.

How does it work? Shunra\Cloud alters the way IP traffic flows within its host. Instead of processing the IP traffic immediately, each IP packet sent to or received by the host is delayed, duplicated, fragmented, or dropped according to the required emulation parameters. Shunra\Cloud can be installed on a client, server, or on a dedicated PC configured as a router or modem, allowing users to emulate and test a link between any Ethernet device.

Installing Shunra/Cloud v4.0 was very straightforward and we encountered no difficulties. After installing, we ran the application, which consists of a very easy to use graphical user interface.

We then single-clicked on the WAN cloud icon, which brought up the customizable parameters for the WAN. From this screen we were able to set five major parameters: Latency, packet loss, packet effects, link faults, and congestion. Each of the five major parameters have useful settings that can be changed to suit your testing requirements. For instance, under the �Latency� settings screen, we were able to choose fixed latency, uniform distributed latency, normal distributed latency, and linear latency. The �Packet Loss� screen also has several interesting parameters, including periodic packet loss, random loss by percentage, burst loss, and Gilbert-Elliot Loss.

In addition, we were also able to specify symmetric bandwidth (same uplink and downlink bandwidth) or asymmetric bandwidth (uplink and downlink have differing bandwidths) for each of the two gateways. The asymmetric setting can be useful in asymmetric network scenarios such as DSL or cable broadband. Shunra\Cloud can accurately emulate physical links from 2.4 Kbps up to 10 Mbps. To emulate the backbone infrastructure of rates higher than 10 Mbps Shunra offers another product called Shunra\Storm. Shunra\Storm supports links ranging from 2.4 Kbps up to 622 Mbps.

One useful feature is Shunra\Cloud�s �Packet Overhead� setting. Since a gateway often adds overhead bytes to the IP data that flows through the gateway NIC, you can use this parameter to specify the number of bytes, in order to emulate the bandwidth consumption they impose on the network. Another useful feature is something called the �CloudCatcher,� which essentially allows you to play back a profile recorded using the CloudCatcher. This will take all the �real-world� recorded samples of latency and select each at random. This is useful for creating jitter effects (rapidly changing network conditions) on the network. Since VoIP, video, and other streaming media are sensitive to jitter, Shunra\Cloud is very useful in testing these types of applications.

Another interesting feature is that the software lets you import a simple test file of latency values. The software can then randomly pick each of these latency values at specified intervals. Shunra\Cloud also offers a variety of automated testing methods. Three command line options are available that can be scheduled. CloudPlay.exe and CloudStop.exe commands enable you to activate pre-configured WAN emulation files. Cloud.exe lets you specific all the various testing parameters specified on a single command line. Finally, the source code to their API is supplied with Shunra\Cloud, enabling C/C++ applications to integrate into it.

To determine the root cause of any performance degradation, Shunra\Cloud provides a wide variety of reports and graphs including total throughput per direction, throughput per IP, packet lists, and network statistics.

There wasn�t much to complain about with this product. It is very simple to use and easy to navigate. We only discovered two minor usability complaints. One is that you have to close the current emulation file in order to open a new one. We�d like to be able to simply open a new emulation file, which would close the current one. Or perhaps Shunra could add MDI support so that we could have multiple emulation files open at once and then quickly switch between all of them from the �Window� menu.

Our second usability suggestion is we tried to open a sample emulation file from the Samples folder from within the Cloud software and none of the samples showed up in the window. We then changed the drop-down file-type list from �WAN Emulation File� to �Cloud Emulation File/Template� and then the samples showed up.

Shunra\Cloud is an excellent solution for application developers to test and develop their applications first, which will minimize rollout risk. By using a tool such as Shunra\Cloud you can certainly cut costs, saving time and resources by pinpointing and fixing problems before deployment. In addition this software can be used to help determine what sort of service level agreements (SLAs) you can expect to offer your customers, as well as determine the ROI on network upgrades. Overall, TMC Labs was very impressed with Shunra\Cloud 4.0 and would highly recommend it for your network testing/emulation needs.

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