Flow routing and its performance analysis in optical IP networks

Optical packet-switching networks deploying buffering, wavelength conversio n and multi-path routing have been extensively studied in recent years to p rovide high capacity transport for Internet traffic. However due to packet- based routing and switching, such a network could result in significant dis order and delay variation of packets when they are received by end users, t hus increasing the burstiness of the Internet traffic and causing higher-la yer protocol to malfunction. This paper addresses a novel routing and switc hing method for optical IP networks - flow routing, and its facilitating pr otocol. Flow routing deals with packet-flows to reduce flow corruption due to packet out-of-order, delay variation and packet loss, without using comp licate control mechanism. Detailed performance analysis is given for output -buffered optical routers adopting flow routing. Two flow-oriented discardi ng techniques, i.e., flow discard (FD) and early flow discard (EFD), are di scussed. Compared with optical packet-switching routers, a remarkable impro vement of good-throughput is obtained in the optical flow-routers, especial ly under high congestion periods. We conclude that EFD behaves as a robust technique, which is more tolerant than FD to the change of traffic and tran smission system factors.