Deadlock-Free Routing in an Optical Interconnect for High-Speed Wormhole Routing Networks

The Supercomputer SuperNet (SSN) is a two-level hierarchical high-speed network. The lower level is a High Speed Electronic mesh fabric; the higher level is a WDM optical backbone network interconnecting the high-speed fabrics distributed across a campus or metropolitan area. The salient characteristics of this architecture are the use of wormhole routing and backpressure hop-by-hop flow control mechanism. Because of these features, deadlocks are possible in SSN. In this paper, we address the issue of deadlock-free routing which is an essential prerequisite for the proper operation of SSN. To this end, we first present a deadlock free routing scheme for the WDM backbone which is implemented with a shufflenet multihop virtual topology. We use the notion of virtual channels to obtain mappings of virtual channels to physical channels such that deadlock-free routing is achieved for any (p; k) shufflenet (uni and bidirectional). Then, we compare the virtual channels scheme with the more con..