Fluid analysis of early message discarding policy under heavy traffic

A message (or a frame) is a group of consecutive packets (or cells in ATM terminology). Often a loss of one packet from the message can result in the loss of the whole message. Selective message discarding policies have been proposed to achieve the twin goal of increased goodput and reduced network congestion by discarding the packets which do not belong to (or have potential of not belonging to) good messages. In this paper we provide a fluid analysis of early message discard. We obtain approximations for performance metrics which are valid for heavy traffic conditions. In particular, we obtain exact expressions for the distribution of the stationary workload process and the fluid goodput ratio. Our analytical results will be quite helpful in selecting an optimal discarding threshold, in studying the sensitivity of goodput ratio to different parameters and also in problems related to buffer and/or capacity dimensioning to achieve a desired quality of service.