A new interconnection network for massively parallel computing is introduced. This network is called an Optical Multi-Mesh Hypercube (OMMH) network. The OMMH integrates positive features of both hypercube (small diameter, high connectivity, symmetry, simple control and routing, fault tolerance, etc.) and mesh (constant node degree and scalability) topologies and at the same time circumvents their limitations (e.g., the lack of scalability of hypercubes, and the large diameter of meshes). The OMMH can maintain a constant node degree regardless of the increase in the network size. In addition, the flexibility of the OMMH network makes it well suited for optical implementations. This paper presents the OMMH topology, analyzes its architectural properties and potentials for massively parallel computing, and compares it to the hypercube. Moreover, it also presents a three-dimensional optical design methodology based on free-space optics. The proposed optical implementation has totally space-invariant connection patterns at every node, which enables the OMMH to be highly amenable to optical implementation using simple and efficient large space-bandwidth product space-invariant optical elements.

Two important parameters of a network for massively parallel computers are scalability and modularity. Scalability has two aspects: size and time (or generation). Size scalability refers to the property that the size of the network can be increased with nominal effect on the existing configuration. Also, the increase in size is expected to result in a linear increase in performance. Time scalability implies that the communication capabilities of a network should be large enough to support the evolution of processing elements through generations. A modular network enables the construction of a large network out of many smaller ones. The lack of these two important parameters has limited the use of certain types of interconnection networks in the area of massively parallel computers. We present a new modular optical interconnection network, called an optical multimesh hypercube (OMMH), which is both size and time scalable. The OMMH combines positive features of both the hypercube (small diameter, high connectivity, symmetry, simple routing, and fault tolerance) and the torus (constant node degree and size scalability) networks. Also presented is a three-dimensional optical implementation of the OMMH network. A basic building block of the OMMH network is a hypercube module that is constructed with free-space optics to provide compact and high-density localized hypercube connections. The OMMH network is then constructed by the connection of such basic building blocks with multiwavelength optical fibers to realize torus connections. The proposed implementation methodology is intended to exploit the advantages of both space-invariant free-space and multiwavelength fiber-based optical interconnect technologies. The analysis of the proposed implementation shows that such a network is optically feasible in terms of the physical size and the optical power budget.

No abstract

A new design methodology for constructing optical space-invariant hypercube interconnection networks for connection of a two-dimensional array of inputs to a two-dimensional array of outputs is presented. The methodology permits the construction of larger hypercube networks from smaller networks in systematic and incremental fashion. It is shown that the proposed methodology greatly improves area utilization as compared with previous methods. An example network is provided that illustrates the proposed design method. Owing to their totally space-invariant nature, the resulting three-dimensional hypercube networks are highly amenable to optical implementations by use of simple optical hardware such as multiple-imaging components and space-invariant holographic techniques. We present space-invariant optical implementation technique for the realization of such networks. A theoretical analysis of the physical limitations of the implementation method is also presented. The analysis indicates that two-dimensional arrays of 512 × 512 nodes interconnected in a hypercube (18-cube) topology could be implemented.

No abstract