Max-min Fair scheduling of variable-length packet-flows to multiple servers by deficit round-robin

Abstract

We describe a scheduler based on deficit-round robin (DRR) for multiple servers of multiple packet-flows, where each packet-flow may be served by only a subset of available (preferred) servers. The scheduler uses a token allocation algorithm that is weighted max-min fair, and so we've called it Multi-Server Max-min Fair DRR (MSMF-DRR). The scheduler also compensates for potential errors in estimates of server capacities when determining token allocations, and considers service underflow resulting in unused tokens at the end of a round. Numerical examples are given to illustrate how the scheduler itself is weighted max-min fair.