Routers built around a single-stage crossbar and a centralized scheduler do not scale, and (in practice) do not provide the throughput guarantees that network operators need to make e cient use of their expensive long-haul links. In this paper we consider how optics can be used to scale capacity and reduce power in a router. We start with the promising load-balanced switch architecture proposed by CS. Chang. This approach eliminates the scheduler, is scalable, and guarantees 100% throughput for a broad class of tra c. But several problems need to be solved to make this architecture practical: (1) Packets can be mis-sequenced, (2) Pathological periodic tra c patterns can make throughput arbitrarily small, (3) The.
