WALE v1

Download WALE

Technical Report

UTIME

WALE is a Wide Area Link Emulator which gives the flexibility of setting various parameters of a bottleneck link, such as packet send and receive rates, send/receive buffers, send/receive propagation delays, enabling random loss modules, etc.

Any ISP has a high bandwidth LAN (of the order of tens of Mbps, e.g. Ethernet) and a WAN access link with relatively low speeds (of the order of a few Kbps to a few Mbps). To be able to evaluate the ISP's performance, actual tests will have to be conducted on a live, fully functional network. This would imply enabling certain features in communication equipment which could be detrimental to the proper functioning of a commissioned network. To address such a problem of being able to characterize/quantify the network operation in terms of its performance with respect to various parameters, a test-bed emulating the ISP's connectivity to the Internet would be an ideal solution.

An important factor in setting up such a test-bed, is emulating the WAN Access Link. Using complex hardware is costly. Such a link can however be easily implemented by emulating the scenario on popular physical technology such as Ethernet. By changing the TCP/IP stack on a Personal Computer, the rate at which packets are injected into the network can be controlled and other necessary features can easily be added.