Interconnect for commodity FPGA clusters: Standardized or customized?

We demonstrate that a small library of customizable interconnect components permits low-area, high-performance, reliable communication tuned to an application, by analogy with the way designers customize their compute. Whilst soft cores for standard protocols (Ethernet, RapidIO, Infiniband, Interlaken) are a boon for FPGA-to-other-system interconnect, we argue that they are inefficient and unnecessary for FPGA-to-FPGA interconnect. Using the example of BlueLink, our lightweight pluggable interconnect library, we describe how to construct reliable FPGA clusters from hundreds of lower-cost commodity FPGA boards. Utilizing the increasing number of serial links on FPGAs demands efficient use of soft-logic, making domain-optimized custom interconnect attractive for some time to come.