Date Added: Jan 2011
Folded-Clos networks, also referred to as fat-trees, have been widely used as interconnects in large scale high performance computing clusters. The switching capability of such interconnects in the computer communication environment, however, is not well understood. In particular, the concept of nonblocking interconnects, which is often used by system vendors, has only been studied in the telephone communication environment with the assumption of a centralized controller. Such "Nonblocking" networks do not support nonblocking communications in computer communication environments where the network control is distributed. In this paper, the authors investigate folded-Clos networks that are nonblocking in computer communication environments and establish nonblocking conditions for various routing schemes including deterministic routing and adaptive routing.