This paper presents performance characteristics of the CM-5 data network with respect to bandwidth and latency. We present the maximum effective network bandwidth as a function of (1) message size, (2) varying data path through different levels of the network hierarchy, and (3) system load. We also present latency as a function of message size and network hierarchy. In the second part of our evaluation, we present the maximum effective network bandwidth as a function of data flow pattern (2-d and 3-d mesh, stencils, ring, tree, and hypercube) using several variant embedding schemes. Measurements were obtained using CMMD V 1.3.1, Thinking Machine Corporation′s message-passing library, and CMNF V 1.1, a fast message-passing library developed by the Minnesota Supercomputer Center (MSC) for the Army High Performance Research Center (AHPCRC). Using CMNF we were able to observe measurements which were very close to actual hardware capabilities.