A Comparison of Three Gigabit Technologies: SCI, Myrinet and SGI/Cray T3D

Abstract

In 1993 Cray Research shipped its first T3D Massively Parallel Processor (MPP) and set high standards for Gigabit/s SAN (System Area Network) interconnects of microprocessor based MPP systems sustaining 1 Gigabit/s per link in many common applications. Today, in 1999, the communication speed is still at one Gigabit/s, but major advances in technology managed to drastically lower costs and to bring such interconnects to the mainstream market of PCI based commodity personal computers. Two products based on two completely different technologies are readily available: the Scalable Coherent Interface (SCI) implementation by Dolphin Interconnect Solutions and a Myrinet implementation by Myricom Inc. Both networking technologies include cabling for System Area Networking (SAN) and Local Area Networking (LAN) distances and adapter cards that connect to the standard I/O bus of a high end PC. Both technologies can incorporate crossbar switches to extend point to point links into an entire network fabric. Myrinet links are strictly point to point while SCI links can be rings of multiple nodes that are possibly connected to a switch for expansion. In the mean time two Internet technologies emerging from the inter-networking world also arrived at Gigabit speeds—ATM (Asynchronous Transfer Mode) and Gigabit Ethernet. Based on the specification and their history those two alternatives are related to the evaluated technologies Myrinet and SCI.KeywordsMessage PassingDirect DepositRemote MemoryMain ProcessorContiguous BlockThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.