Will Optical Replace Electronic Packet Switching?
Packet switches (or routers) are key hardware components in the Internet, directing information through the network from its source to its destination. Incoming data packets arrive at routers on optical-fiber transmission links and are converted to electrical form by optical-to-electronic (O/E) converters for processing. Similarly, outgoing data passes through E/O converters before traversing the next optical link in the network. An optical packet switch is similar to an electronic router but does not require O/E and E/O converters.1¨C3 Instead, the data remains in optical form throughout the network, including the switches. Figure 1 shows schematic diagrams of electrical and optical switches.
For a number of years, researchers (including the author) have argued that optical packet switching will become an essential part of the Internet as the size and capacity of the network expand. The approach has several key advantages, including higher bandwidth and data format independence. However, a major obstacle to development of practical hardware has been the lack of a suitable memory technology that can store high-bit-rate optical packets. In an electronic switch, electronic buffer memory provides storage when needed to avoid collisions between outgoing packets on the same output port.
Note that unforseen technology breakthroughs could well change some of our conclusions. However, we hope that our work stimulates discussion and debate on the relative merits of electronic and optical packet switching. If this debate eventuates, it needs to consider the centrally important issue of energy consumption.