If a new application's performance leaves a lot to be desired, developers often point the finger at network folks, who say the network is just fine. Resolving this type of dispute is the forte of Opnet Technologies' IT Guru - a sophisticated tool that provides analysis and modeling of network performance.We recently tested Version 9.0 of IT Guru at West Virginia University's Advanced Network Applications Lab. The product performed as expected, and was very user-friendly in its basic features. For companies in which network performance issues can cost thousands of dollars in lost revenue per minute, the package is invaluable. How we did it Interactive Scorecard and NetResults Archive of Network World reviews Subscribe to the Product Review newsletterStrong data analysisIT Guru's data analysis begins with packet capture. The Application Characterization Environment (ACE) module includes a capture agent that can be installed on various machines throughout the network. This lets you measure performance from various vantage points across the network. The ACE module also can import packet traces from network analyzers, such as Network Associates' Sniffer series.After visually inspecting traffic, ACE takes the raw data and filters it by various criteria. This is where the performance analysis begins. The ability to view network and application performance side by side in a graphical format is a nice feature, which makes it easy to determine the location of performance issues and delays.The AppDoctor module offers spreadsheet-like diagnostic and statistic windows that help determine if delays are occurring in the application or network. AppDoctor analyzes different parameters, including average packet size, retransmissions, the number of no acknowledgements, and errors. Any out-of-range values are highlighted in yellow by default. Although you can set the out-of-range thresholds, we found the default settings adequate for most diagnoses. AppDoctor gives basic explanations of the delay types it identifies and offers possible solutions. While far from comprehensive, we found the information useful.Advanced controls in the Quick Predict module let you introduce variables that can help predict the effect of changes on the network. These variables include changing the bandwidth, latency, packet loss, link optimization, payload\/packet size and TCP window size (setting the optimum TCP window size is often overlooked in network performance).While a comprehensive network analysis was beyond the scope of this review, we modeled various changes within the network to see how it would affect our bandwidth. When we decreased bandwidth or increased latency, we could see that our throughput was significantly throttled back. This what-if analysis is especially helpful in tweaking the performance of multimedia applications and networks to assure smooth streaming video or audio.ReportingIT Guru's Web-based reports mirror the reports of the package itself. No new information or views are offered. The Web-based reports were easy to browse through and sometimes presented data with more clarity than the IT Guru graphical user interface. Help is available on several charts in the Web reports, such as the Application Message chart and the Network Packet Analysis, but is not available with any of the AppDoctor reports. We think it would have been better to provide consistent help on all Web reports.Installation and documentationIT Guru's installation was straightforward and took less than 15 minutes. When it completed its work, the installer simply quit. We would have preferred a confirmation that the installation had been completed successfully. The documentation is on CD and requires Adobe Acrobat Reader, but the helpful, documentation installer offers to install Acrobat Reader if it isn't already on the system. Taking up nearly 50M bytes, the documentation is well laid out, easy to use and includes a large number of examples and tutorials. There is no printed version available - something we felt should be offered in a product this comprehensive.A note on costOverall the product performed as expected. The basic IT Guru features (which Opnet says are most often used by its customers) are user-friendly. Beyond this, the product is detailed and feature-rich, but also contains a steep learning curve. We found ourselves addicted to the more advanced features, and wished we could have more time to dig into these capabilities. With adequate behind-the wheel experience, a network technician could find the product very useful in evaluating the effects of new applications and network changes without harming the production network.However, this is an expensive package. The costs for typical installations of IT Guru range from $40,000 up to $100,000, based on the number of modules and customization purchased. At first we were put off by the cost. How many corporations can afford a software package that costs as much as a high-end router? Then we realized that companies where network performance issues can cost thousands of dollars in revenue per minute would find the package invaluable. For a bank, a commerce Web site, or manufacturing facility, the decision is not whether you can afford IT Guru, but if you can afford not to use it. IT Guru 9.0 (Windows 2000) 4.15 Rating Company: Opnet Technologies, (240) 497-3000 Cost: $40,000 to $100,000 based on modules and customized models purchased. Pros: Powerful and sophisticated application\/network performance analysis; accurate modeling and analysis of performance issues; basic features easy to learn and use. Cons: Very expensive; not enough feedback during installation; steep learning curve on advanced features; inconsistent Web report help. \u00a0 IT Guru 9.0 Accuracy 40%\u00a0 4.5 Features 30%\u00a0 4.5 Ease of use 15%\u00a0 3 Documentation 10%\u00a0 3.5 Installation 5%\u00a0 4 TOTAL SCORE 4.15 \u00a0Individual category scores are based on a scale of 1 to 5. Percentages are the weight given each category in determining the total score. Scoring Key: 5: Exceptional showing in this category. Defines the standard of excellence; 4: Very good showing. Although there may be room for improvement, this product was much better than the average; 3: Average showing in this category. Product was neither especially good nor exceptionally bad; 2: Below average. Lacked some features or lower performance than other products or than expected; 1: Consistently subpar, or lacking features being reviewed.