We provide a comprehensive survey of packet-switched ring metro WDM networks.

Recent technological advances allow for the dynamic setup and release of end-to-end circuits consisting of Ethernet segments at the ends mapped on to Ethernet-over-SONET long-distance optical circuits. We call these Dynamically Reconfigurable Ethernet/Ethernet-over-SONET (DREEoS) circuits. For file transfers across end hosts that can be connected by a DREEoS circuit, we propose that, in most cases, the sending end host should first attempt to set up a DREEoS circuit, and if rejected, fall back to the TCP/IP path. If the DREEoS circuit setup is successful, the end host will enjoy a much shorter file transfer delay than with the TCP/IP path. For example, a 1GB file transfer on a TCP/IP path with a round-trip time of 50ms, link rate of 1Gbps, and a loss probability of 0.0001 takes 395.7sec, while on a DREEoS circuit with the same link rate, the transfer time is 8.08sec. The availability of the fallback TCP/IP path allows DREEoS service to be introduced gradually into optical networks. At low loads, the network can be operated at high call blocking probabilities to achieve high utilization. As loads increase, the network can be engineered to retain high utilization while simultaneously offering low call blocking probabilities. An important component of this proposal is hardware acceleration of signaling protocol implementations. This results in low call setup delays allowing for the DREEoS option to be attempted even for small file sizes. We compare mean delay incurred with a DREEoS circuit attempt against the mean delay incurred with directly choosing the TCP/IP path for different values of call blocking probability in the circuit-switched network, probability of packet loss in the IP network, round-trip times, link rates, etc.