A virtual circuit deflection protocol

We propose a communication protocol, called the virtual circuit deflection (VCD) protocol, which combines some of the individual characteristics of vi rtual circuit switching and deflection routing. An advantage of the VCD pro tocol over previous (datagram) deflection schemes is that deflections in th e former occur on a per session basis (or a per subsession basis, if sessio ns need to be split to find adequate capacity on the outgoing links), while in the latter, they occur on a per packet basis. This makes packet reseque ncing at the destination considerably easier to accomplish in the VCD proto col than in datagram deflection schemes. The VCD protocol exploits the stor age arising from the high bandwidth-delay product of optical fibers to prov ide lossless communication with little buffering at the switches and withou t the need for advance reservations. This makes it particularly suitable fo r networks that use optical switching, where buffers are expensive to imple ment with current optical technology. We present a simple implementation of the VCD protocol for such networks, which requires only limited buffering, accomplished through the use of a minimal number of optical delay lines. W e also analyze the performance of the protocol for the Manhattan Street net work topology by using new analytical models, In particular, we examine the effect of the traffic load and the network size on the throughput and the length of the paths followed by the sessions, and compare the analytical re sults obtained with corresponding simulation results, Our results indicate that the VCD protocol is efficient under both light and heavy traffic condi tions, especially when the link capacities are large compared to the basic rate of individual sessions, as is expected to be the case in future multig igabit networks.