Historically, network testbeds have focused on issues relating to either high bandwidth or advanced services. For various reasons nearly all testbeds carry little traffic beyond a few chosen applications. Networks that carry heavy "routine" traffic are off limits to network researchers. This deep dichotomy in network usage has prevented nearly all effective research in traffic dynamics. We need to have a way to study how traffic is affected by other traffic, in the presence of advanced services. Specifically, we are proposing the development of a Traffic Dynamics Testbed (TDT). This testbed would not only provide very high bandwidth links based on leading edge technologies, but also allow for the broader study of how all layers of this infrastructure interact and support a wide range of traffic types and services. Traffic restrictions associated with previous testbed initiatives have created an artificial traffic-less environment. A critical component of the Traffic Dynamics Testbed would be the inclusion of