In this paper we present an in-depth description of the Quadrics
interconnection network (QsNET) and an experimental performance
evaluation on a 64-node Alphaserver cluster.  We expose the
performance and the scaling properties of the network by using a
collection of benchmarks, using permutation patterns, congested
traffic with several types of hotspots and I/O traffic.  The
experimental results indicate that the QsNET provides excellent
performance in most cases, with excellent contention resolution
mechanisms.