A dynamic routing control system for high-performance PC cluster with multi-path Ethernet connection

VLAN-based flexible, reliable and expandable commodity network (VFREC-Net) is a network construction technology for PC clusters that allows multi-path network routing to be configured using inexpensive Layer-2 Ethernet switches based on tagged-VLAN technology. Current VFREC-Net system encounters problems with traffic balancing when the communication pattern of the application does not fit the network topology, due to its static routing scheme. We have developed a framework to solve this problem by allowing dynamic rewriting of the routing table from the application level. The basic function of modifying the VLAN-ID assignment for the communicating node pair from user application is supported. Using this function, it is possible to dynamically select the path to the destination from multiple paths. We also provide an API library for MPI programming to use the above framework, and confirmed its effectiveness through communication optimization on the NPB Kernel-CG benchmark.