With
in today's Internet data is transported using wavelength division multiplexed
(WDM) optical fiber transmission system that carry 32-80 wavelengths modulated
at 2.5gb/s and 10gb/s per wavelength. Today's largest routers and electronic switching
systems need to handle close to 1tb/s to redirect incoming data from deployed
WDM links. Mean while next generation commercial systems will be capable of single
fiber transmission supporting hundreds of wavelength at 10Gb/s and world experiments
have demonstrated 10Tb/shutdown transmission.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
Moor's law.
The bandwidth mismatch between fiber transmission systems and electronics
router will becomes more complex when we consider that future routers and switches
will potentially terminate hundreds of wavelength, and increase in bit rate per
wavelength will head out of beyond 40gb/s to 160gb/s. even with significance advances
in electronic processor speed, electronics memory access time 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
opto-electronic interfaces dominate the power dissipations, footprint and cost
of these systems, and do not scale well as the port count and bit rate increase.
Hence it is not difficult to see that the process of moving a massive number of
packets through the multiple layers of electronics in a router can lead to congestion
and exceed the performance of electronics and the ability to efficiently handle
the dissipated power.
