Performance Analysis of Bandwidth Provisioningfor AF~+ VoIP Service Models over DiffServ-basedMPLS Networks

摘要

DiffServ services have been supported by manyrnnetwork systems to provide the preferential treatments to usersrnwith three service classes: Expedite Forwarding (EF), AssuredrnForwarding (AF), and Best Effort (BE) services. One prominentrnhigh speed network system which has enabled the DiffServrnis the Multi-Protocol Label Switching (MPLS) based network.rnHowever, current DiffServ mechanism in MPLS network, eitherrnusing E-LSP or L-LSP, classifies all packets in a LSP as the samernclass. Such design discipline can not solve the myth of tradeoffrnbetween cost and service quality. In this paper, we propose twornnovel service models, AF_(non-RA)~+ and AF_(RA)~+, to enable the E-LSPrnand L-LSP to tradeoff between the two opposing objectives. Thernmajor technical challenge involves how to meet each user’s SLArnrequirement while maximizing system revenue. AF_(non-RA)~+ andrnAF_(RA)~+ services are modeled as two-dimension and one-dimensionrnbirth-death processes respectively to evaluate their performancernunder different traffic scenarios. The numerical results show thatrnboth proposed AF extension service models take advantages ofrnservice guard and cost-savings features from EF and AF-class.rnThe total bandwidths can be assigned to tune the alternativernissues of call blocking rate and provisioned bandwidth cost.rnThis study has confirmed that AF_(non-RA)~+ and AF_(RA) meet therncost-effective requirements and provide a practical solution tornDiffServ-based MPLS Networks.