Path-diverse In-order Routing

Abstract

We present Path-Diverse In-Order Routing (PDIOR), an oblivious routing method which guarantees network-level inorder delivery for multi-path routing. Based on Exclusive Dynamic Virtual Channel Allocation (EDVCA), which allows single-path efficient inorder delivery with dynamic virtual channel allocation, PDIOR extends the same guarantees to routing schemes where each flow may be routed via more than one path. As with EDVCA, PDIOR avoids the overheads inherent in reordering packets at the destination core, and requires only minor, inexpensive changes to traditional oblivious router architectures: for example, an implementation of PDIOR on 8×8 mesh network with 4 VCs per port requires 492 bytes of memory per node, while inorder packet delivery in a comparable conventional network may requires tens to hundreds of kilobytes of reorder buffer memory at each node.