Initial Studies of SCI LAN Topologies for Local Area Clustering," First International Workshop Copyright SCIzzL 1995, all rights reserved 21 Posted on the SCIzzL WebServer by special arrangement with Bit 3

A Local Area Network (LAN) can be built using the ANSI/IEEE Standard 1592-1992 Scalable Coherent Interface (SCI) as the underlying hardware protocol. For the LAN, SCI will act as a new physical layer, and traditional protocols (as e.g. TCP/IP) may be run on top of SCI. In a first approach, SCI is used to implement message passing while new protocols and functions that take advantage of the shared memory functionality can be developed. In this paper we do initial studies of throughput and latency at the physical layer for some SCI LAN candidate topologies. This performance will be a hard upper bound for application performance. SCI LANs based on ring, switched star and a mixed topology of hubs and a switched backbone are considered, and simulations are done to show how the performance metrics throughput and latency varies as function of topology and the physical transmission distance of the network. The new point in this study is to focus on the effect of increasing transmission distance to show that a LAN as well as a closely coupled system can be built by using the SCI interconnect. 1