Optical Networking Best Practices Handbook

2.2. OPTICAL SIGNAL PROCESSING FOR OPTICAL PACKET SWITCHING NETWORKS

Within today's Internet, data are transported using WDM optical fiber transmission systems that carry 32 to 80 wavelengths modulated at 2.5 and 10 Gbps per wavelength. Today's largest routers and electronic switching systems need to handle close to 1 Tbps to redirect incoming data from deployed WDM links. Meanwhile, next-generation commercial systems will be capable of single-fiber transmission supporting hundreds of wavelengths at 10 Gbps per wavelength, and world-record experiments have demonstrated 10 Tbps transmission [3].

The ability to direct packets through the network when single-fiber transmission capacities approach this magnitude may require electronics to run at rates that outstrip Moore's law. The bandwidth mismatch between fiber transmission systems and electronic routers becomes more complex when one considers that future routers and switches will potentially terminate hundreds of optical wavelengths, and the increase in bit rate per wavelength will head out beyond 40 to 160 Gbps. Even with significant advances in electronic processor speeds, electronic memory access times only improve at the rate of approximately 5% per year, an important data point since memory plays a key role in how packets are buffered and directed through a router. Additionally, optoelectronic interfaces dominate the power dissipation, footprint, and cost of these systems, and do not scale well as the port count and bit rates ...