The vast expansion in the use of the Internet over the past two years resembles the upsurge in tourists traveling to an increasingly popular resort. Traveling along the main highway to the resort at the start of a summer weekend, the stream of tourists experiences a series of bottlenecks whenever the six-lane highway narrows down to four lanes to cross bridges or pass other obstructions.
Internet users face similar kinds of bottlenecks.
These take the form of hub regions that must switch pulses of light moving rapidly and efficiently along optical fibers onto new routes. At those hubs, the system must convert the light pulses into electronic packages to permit them to travel through the switch. Once rerouted, the packets are converted back into light. The conversion and reconversion slows down the entire process. David Bishop, director of micromechanial research at Lucent Technologies' Bell Labs, said that any sort of electronic system at the end of an optical fiber will inevitably cause a traffic jam because it lacks the capacity to deal with the fiber's bandwidth.