ABSTRACT: We examine the performance of high-bandwidth multimedia applications over high-speed wide-area networks, such as the vBNS (Internet2). We simulate a tele-immersion application that sends 30 Mbps (2,700 datagrams per second) to various sites around the USA, and measure network- and application-level loss and throughput. We found that over the vBNS, performance is affected more by the packet-rate generated by an application than by its bit-rate. We also assess the amount of error recovery and buffering needed in times of congestion to present an effective multimedia stream to the user. Lastly, we compare our application-level measurements with data taken from a constellation of GPS-synchronized network probes (IPPM Surveyors). The comparison suggests that network-level probes will not provide information that a multimedia application can use to adapt its behavior to improve performance.