gned bandwidth, its spare bandwidth shall be fairly shared by other PHBs. EF PHB AF11 PHB LAF11 AF21 PHB LAF21 IP_BW AF31 PHB LAF31 IP_BW_NRT AF41 PHB LAF41 BE PHB Figure 7.1: Dimensioning for IP DiffServ-based QoS Structure The following presents the proposed analytical approach to estimate the application performance of each service class and then in turn to be used for dimensioning the lub link bandwidth for satisfying desired application QoS criteria of all service classes. Firstly the following parameters are defined: - Let IP BW denote the total IP bandwidth; Let IP BW NRT be the total bandwidth allocated for NRT traffic, i.e. AF and BE PHBs; Let LEF denote the bandwidth used or reserved by the EF PHB depending on the bandwidth allocation scheme as mentioned above; Let rpeak__k denote the peak rate of the bearer service (i.e. RAB service) for the service class k that is carried on the Kth PHB of a AF or BE PHB; 7.3 Dimensioning for Elastic Traffic Let Nk denote the maximum allowed number of flows for the service class k; Let Wk denote the WFQ weight of the service class k; Let Lk be the mean offered traffic of the service class k; Let Xk denote the average file size of the service class k. The following explains the detailed steps of calculating the average application delay with the M/G/R-PS model for the elastic traffic of the service class k that is carried on the Kth PHB of an AF or BE PHB: (1) The total available capacity for transmissions of all NRT elastic service classes (denoted as IP_BW_NRT) is obtained by subtracting the bandwidth used for the RT traffic from the total IP bandwidth, i.e. .IP_BW_NRT=(IP_BW -Lef) = (2) Ck denotes the available IP bandwidth that can be used for the service class k (carried with the kth PHB), which consists of not only the bandwidth allocated by the WFQ scheduling for the kth PHB, but also the bandwidth which has not been utilized by all other PHBs. It calculated with the following equation: C =IP_BW_NRT (7.1) In the equation above, the first term represents allocate