| Large traditional voice carriers are just beginning to merge their existing Public Switched Telephone Network (PSTN) with their data networks using Voice over Internet Protocol (VoIP) or Voice over Asynchronous Transfer Mode (ATM). The method being considered by many carriers for maintaining Quality of Service (QoS) for VoIP is reservations based admission control. The foundation for reservations based admission control for VoIP is Multiprotocol Label Switching (MPLS) with some type of bandwidth reservation capability such as Resource ReSerVation Protocol (RSVP) or Constraint Routed-Label Distribution Protocol (CR-LDP). The approach used in this research is called Delay Based Congestion Detection and Admission Control (DBCD/AC), a form of Endpoint Admission Control. DBCD/AC is means for the edge devices, such as media gateways, to detect impending congestion in the core based on delay measurements and analysis. When impending congestion is detected the edge devices refuse new incoming connections to the media gateways to mitigate the congestion. This research examines the characteristics of DBCD/AC including the ability to minimize delay, ability to detect congestion, ability to mitigate congestion, ability to provide fairness, ability to coexist with best effort traffic, ability to provide good traffic utilization, ability to scale, and ability to provide voice quality, in an effort to determine if DBCD/AC is a workable alternative to a reservations based admission control approach. |
