The effects of data locality on FDDI-based schemes at gigabit speeds

This paper explores the effects of locality on the performance of a FDDI-based multinetworking environment and compares this to a scaled FDDI approach. Both of these schemes have been presented to the Standards Committee for consideration in migrating the FDDI protocols to gigabit speeds. One is a simple linear scaling (10×) of the FDDI protocol to reach the gigabit speed, and the second, presented by these authors, is a hierarchical scheme which preserves the existing FDDI standards and defines an interconnection network that acts as a backbone to the underlying FDDI networks. An introduction to both network schemes is presented. The average network access delay in the hierarchical network scheme is affected by the locality of the data traffic since data traffic has to traverse two networks if it is not local. A numerical method is presented which allows access to delay results with various network configurations. In the scaled approach there is only one network, thus eliminating the effects of data locality on the performance of the network. The paper is concluded with a discussion of the pros and cons of the two schemes