HORNET: A packet-switched WDM metropolitan area network

The bursty nature of data traffic at the metropolitan area network (MAN) level, if future networks, will result in inefficient and underutilized SONET networks. If data traffic grows and dominates future transport networks, SONET based MANs will become increasingly bandwidth inefficient. HORNET is a WDM ring network developed to address the problems of data transport in MANs. Employing packet switched transport in a WDM ring, using a CSMA/CA access technique to place packets on the network, in empty time slots on any available wavelength, HORNET takes advantage of the bursty nature of the MAN traffic through statistical multiplexing, resulting in a more efficient utilization of the network bandwidth. We demonstrate a novel CSMA/CA access technique, optical packet transmission, optical packet receiver, and packet routing according to destination-node address. In addition to an experimental effort, we have developed a network model based on an event driven simulator to investigate the performance and characteristics of HORNET for various traffic loads and traffic profiles. We have shown that a CSMA/CA packet-switched transport, such as that developed in HORNET, is more efficient at handling the bursty MAN traffic than a circuit switched approach, such as SONET. With this model we show the benefits of a tunable transmitter in a packet-switched WDM MAN. We found that a tunable transmitter is able to take advantage of imbalances in wavelength utilization, and provides a 45% improvement in packet latency characteristics. We also show that to maintain these benefits the tuning time of the transmitter cannot exceed 10% of the packet transmit time.