Includes bibliographical references.One of the service classes offered by Diffserv is the Assured Forwarding (AF) class. Because of scalability concerns, IETF specifications recommend that microflow and aggregate-unaware active buffer management mechanisms such as RIO (Random early detecLion with ln/Out-ofprofile) be used in the core of Diffserv networks implementing AF. Such mechanisms have, however, been shown to provide poor performance with regard to fairness, stability and network controL Furthermore, recent advances in router technology now allow routers to implement more advanced scheduling and buffer management mechanisms on high-speed ports. This thesis evaluates the performance improvements that may be realized when implementing the Diffserv AF core using a hierarchical microflow and aggregate aware buffer management mechanism instead of RIO. The author motivates, proposes and specifies such a mechanism. The mechanism. referred to as H-MAQ or Hierarchical multi drop-precedence queue state Microflow-Aware Quelling, is evaluated on a testbed that compares the performance of a RIO network core with an H-MAQ network core
