WAN emulation is
free software. Developed by TCS, published by Free Software Foundation.
It can modify or redistributed on terms of GNU General Public License
version 2.
Rigorous performance testing and optimization is a critical factor in the successful delivery of any business application. Yet frequently the performance of deployed applications doesn’t live up to business requirements or end-user expectations. One reason behind these unpleasant “surprises” is the fact that most performance staging labs only test the application with local users (in a local area network (LAN) environment), while the fully deployed application is used by a variety of end-users, some local and others accessing the application remotely over different network links. The different network conditions that exist between end-users and application servers have a tremendous effect on the overall performance that remote end-users experience. This deviation from performance test results obtained in the lab is further exacerbated for N-Tier applications where each tier may reside in a different geographical location with its own unique set of network conditions.
Network Emulation tools can be used to accurately replicate existing or projected conditions in the distributed production environment – including infrastructure, application traffic and the distribution of end-users.
Rigorous performance testing and optimization is a critical factor in the successful delivery of any business application. Yet frequently the performance of deployed applications doesn’t live up to business requirements or end-user expectations. One reason behind these unpleasant “surprises” is the fact that most performance staging labs only test the application with local users (in a local area network (LAN) environment), while the fully deployed application is used by a variety of end-users, some local and others accessing the application remotely over different network links. The different network conditions that exist between end-users and application servers have a tremendous effect on the overall performance that remote end-users experience. This deviation from performance test results obtained in the lab is further exacerbated for N-Tier applications where each tier may reside in a different geographical location with its own unique set of network conditions.
Network Emulation tools can be used to accurately replicate existing or projected conditions in the distributed production environment – including infrastructure, application traffic and the distribution of end-users.
To sum up on a high level — the benefits of using WAN Emulation tools are:
- WANem is a freeware.
- mitigate applications deployment risk
- find errors before deployment
- test new WAN topologies and technologies
- emulate remote users experience
- stress models of the network to find vulnerabilities
Minimum an i386 based PC with 1 CPU, 512 MB RAM and 1 Network interface card – 100 Mbps (preferably 1 Gbps).
2.1 Applications supported by the WANem(but not limited to)
1. Web applications,
2. Video Streaming
3. Interactive applications – telnet like application.
2.2 Setting up WANem
WANem is distributed in the form of a bootable CD with Linux Knoppix O/S. This CD comes with WANem preinstalled. There are no installation steps. When an i386 architecture based PC is booted with the PC WANem is ready for use.
*Refer WANem user guide for more information on launching WANem and usage.
Drawbacks of WANem:
1. Multiple NIC cards when there is need for performing distributed load generation.
2. Dedicated PC required for WANem setup.
3. Network address translation needs to be done when a client application is running on a different network.
4. Cannot be integrated with LoadRunner.
5. Installation is relatively difficult.
Conclusion
WAN emulation is free software and hence cost effective. Advanced network options present in WAN emulation keeps trust and usability of the tool on the same level as of any other contemporary network emulation tool.
wan emulation:
Some
times client may not have Load injectors in different geographic
locations and want to generate load from different geographic locations
and want to simulate the delays associated with a different geographic
distribution using the load injectors in the lab. Then we need
WAN emulation.
Below are some tips while using WAN Emulator.Running WAN Emulation over a firewall:
If the agent connection type is defined as HTTP with proxy, the proxy server must be excluded from WAN emulation. Exclude the proxy server using the Load Generators > Details > WAN Emulation dialog.
WAN Emulation does not support the token-ring and Ethernet-token ring hybrid interfaces.
The WAN Emulator driver installation will disconnect your open network connections.
To uninstall the WAN Emulator driver, run Uninstall WanDriver.bat from the WAN Emulator directory on the LoadRunner CD.
To reset the WAN Emulator driver, run msh_reset.exe from the LoadRunner bin directory, or from the WANEmulator directory on the LoadRunner CD.
It is recommended not to install the Network Analyzers software on the same load generator machine where WAN emulation resides. This may cause false readings and affect measurements.
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