Routing in infiniBand™ torus network topologies

InfiniBand is an interconnect standard for communication between processing nodes and I/O devices as well as for interprocessor communication (NOWs). The InfiniBand architecture (IBA) defines a switch-based network with point-to-point links whose topology can be established by the customer. When the performance is the primary concern regular topologies are preferred. Low-dimensional tori (2D and 3D) are some of the regular topologies most widely used in commercial parallel computers. Routing in torus requires the use of virtual channels. Although InfiniBand provides support for deterministic routing and virtual channels, they are selected at each switch by service level (SL) identifiers associated to packets and do not depend on packet destination. This makes routing algorithm implementation more complex. In particular, a large number of SLs may be required, which is a scarce resource. We analyze the way several routing strategies can be applied in tori InfiniBand networks, also evaluating their resource requirements. In particular, we analyze and compare the well-known e-cube and up*/down* routing algorithms and the flexible routing algorithm recently proposed