System and method for efficiently routing data packets in a computer

Abstract

A method and system for efficiently routing data packets in a computer interconnect includes a plurality of nodes forming a ringlet, generally including two connections between each pair of nodes configured to allow communication in either direction between each pair of nodes. One sequence of such connections forms a run moving,-for example left-to-right between a series of nodes. The other sequence of connections forms a right-to-left run. Selected nodes are configured to provide two cross-over paths, each from one run to the other, so the two runs are linked to form a circle or ringlet. One or more selected nodes provide an optional connection between the two runs, thus allowing a fast path or short cut to the opposing run. A fast path may include a uni- or bidirectional cross through path in an intermediate node. In one preferred embodiment, a single node can provide both cross-over paths, but can also support a cross-between path for each run, allowing a packet to continue on the same run, rather than the default path that crosses over to the opposite run. The method and system includes data information in a packet that can be used to decide whether to switch the packet through a fast path or to let it continue on the 'normal' path. Routing decisions are based on a path field within each packet. This field is updated when taking a faster path (for example, a cross-through or cross-between path). The update techniques allow data packet path lengths to be reduced, while also providing a packet-aging capability. A scrubber is provided to manage packet aging and to remove packets that have not been removed from the ringlet but are no longer useful.