Dimensioning aggregated voice traffic in MPLS nodes

MPLS offers a efficient transport scheme and traffic engineering capabilities for real-time VoIP. However, at the transport plane, the bandwidth reserved for voice traffic is a key parameter necessary to ensure performance guarantees for VoIP communications. This paper addresses this important piece of traffic engineering: determining the bandwidth requirements for voice traffic aggregated. To achieve our goal we first define a model for a generic voice source which embodies any current type of voice source (which we name Generalized VoIP source). Then, we extend the fluid model with our new GVoIP source to obtain a loss and delay prediction for each multiplexer node. Finally, we design a simple but efficient dimensioning algorithm that provides the bandwidth requirement for a desired performance when multiplexing a number of homogeneous GVoIP sources. Using of dimensioning algorithm we compare the bandwidth requirements for two transport schemes VoIP over MPLS and VoMPLS. Results confirm that our extended multiplexing analytical model improves the estimation of the bandwidth requirement of a voice traffic trunk over MPLS, whereas any other on-off based dimensioning model is not valid for these kind of codecs.