Abstract: When a disaster or emergency occurs, one of the most pressing needs is to establish a communication network for the first responders at the scene. Establishing and accessing a reliable communication infrastructure at a crisis site is crucial in order to have accurate and real-time exchange of information. Failure in the exchange of timely and crucial information or delay in allocating resources impedes early response efforts, potentially resulting in loss of life and additional economic impact. At a disaster site, the existing communication infrastructure may be damaged and therefore partially or totally unavailable; or, there may not have been previously existing infrastructure (as in the case of remote areas). A communication infrastructure within the context of emergency applications should be reliable, easily configurable, robust, interoperable in a heterogeneous environment with minimum interdependencies, and quickly deployable at low cost. A disaster scene is a chaotic environment which requires a systematic approach to abstract the system, study the flow of information and collaboration among different disciplines and jurisdictions to facilitate response and recovery efforts. We have deployed the wireless mesh infrastructure in several drills at the university campus and in the city as part of the California Institute for Telecommunications and Information Technology (Calit2) NSF-funded RESCUE project (Responding to Crises and Unexpected Events). To evaluate network performance and identify the source(s) of bottleneck, we have captured the network traffic. The lessons learned from test bed evaluations of the network based on real-world scenarios can be applied to future applications to enhance the network design and performance.