Dynamics of End-to-End Bandwidth Allocations in QoS-adaptive Data Connections

Abstract

The paper discusses the dynamics of bandwidth allocations that occur in an end-to-end QoS-aware data transport system over a LAN-MAN. Here, the controlled object is a logical connection that carries the application-level data flows over the service provider's data transport infrastructure. The goal is to allocate just-enough bandwidth, in order to maximize the service-provider revenues. Accurate control of bandwidth allocations with a revenue-oriented goal is quite complex, due to the interactions among various data flows that dynamically share the network capacity in the system. So, we employ an on-line monitor-and-control scheme, aided by heuristics, that iteratively adjusts the bandwidth allocation based on the observed packet loss rate. The bandwidth allocation is increased when the observed packet loss rate exceeds a user-specified threshold, with the increase being proportional to the loss rate (i.e., multiplicative increase). The bandwidth is decreased additively when the loss rate falls below a safe limit. We describe this MIAD-based bandwidth allocation scheme, and study its dynamics. When the LAN-MAN environments provide bandwidth capacities in a stable manner, our MIAD scheme can achieve an optimal bandwidth allocation (in the sense of user-level QoS and service-provider revenues).