The data is now multiplexed into multiple, high-speed optical links running over an optical ribbon fiber. The optical signal is easier to transport to the destination, which could be a switching card where many such connections are made. With the proper framing and coding technique, the system can be made transparent to line cards or switching cards at the ends of connections. This fiber system can act as a building block for the interconnection of cards and chassis. System Issues Topologies have been restricted by the nature of copper-based interconnects in traditional scalable systems such as supercomputers.
Connections are short, so cards and chassis are physically close together.
Placing a supercomputer's elements in close proximity does not pose a problem for system design, since processor intercommunication tends to be local. Supercomputers are typically used to process data related to physical functions, so the processing elements need only hand-off results to their nearest neighbor rather than across the entire system. The algorithms used to solve other problems are usually written for a minimum of global intercommunication. Routers and other networking equipment do not operate locally. An incoming packet may be destined for a port anywhere in the system.