Switcherland: A QoS Communication Architecture for Workstation Clusters 

Hans Eberle, Erwin Oertli
Swiss Federal Institute of Technology
CH-8092 Zurich, Switzerland

Abstract

Computer systems have become powerful enough to process continuous data 
streams such as video or ani-mated graphics. While processing power and 
communi-cation bandwidth of today's systems typically are suffi-cient, 
quality of service (QoS) guarantees as required for handling such data 
types cannot be provided by these systems in adequate ways.

We present Switcherland, a scalable communication architecture based on 
crossbar switches that provides QoS guarantees for workstation clusters 
in the form of reserved bandwidth and bounded transmission delays. Similar 
to the ATM technology Switcherland provides QoS guarantees with the help 
of service classes, that is, data transfers are characterized as variable 
bit rate traffic or constant bit rate traffic. However, unlike LAN 
technologies, Switcherland is optimized for cluster computing in that 
(i) it serves as a backplane interconnection fabric as well as a LAN, 
(ii) it extends support for service classes by also covering the end 
nodes of the network, (iii) it pro-vides low latency in the order of 
one microsecond per switch, and (iv) it uses a communication model based 
on a global memory to simplify programming.