The effective bandwidth of a traffic process is a convenient summary of its statistical characteristics.
Standard queueing models are only an approximation to what goes on in the Internet. The cornerstone of Internet is the combined input/output-queued crossbar switch, the heart of most routers. Queueing theorists have so far paid little attention to these devices. I believe that modern advances in queueing theory may have significant implications for switch design.
W.Willinger's work on long-range dependence has had a huge impact on the way queueing theory is applied.
One very good result of the work on long-range dependence is the increased attention given to traffic measurement.
Queueing theory only describes a small aspect of the Internet: what happens to packets of data once they have been sent. To expand our view, we must look at the end-systems that generate the data. Doing so leads us to rethink the entire network architecture---to migrate control of the network towards individual users. Researchers from Cambridge are at the forefront of this work.
See a list of papers maintained by F.P.Kelly, and especially Resource pricing and the evolution of congestion control, R.J.Gibbens and F.P.Kelly.