 capacity for elastic traffic Celastic can be derived iteratively from equation (6.26) and (6.27) given a desired application QoS. Then from equation (6.37), the total required capacity for the lub link Club can be obtained with equation (6.43), where Lcs denotes the mean traffic load of the circuit-switched traffic carried on the lub link. Club = Celastic + Los (6.43) 6.3 Dimensioning for Elastic Traffic In other cases, elastic traffic and circuit-switched traffic can be handled by separated bandwidth portions, as shown in Figure 6.36. One part of the link capacity is exclusively dedicated to circuit-switched traffic which is denoted as Ccs, the other part is exclusively dedicated to elastic traffic which is denoted as Celastic Such bandwidth partitioning can be realized by employing specific traffic policy units at the network nodes such as rate limiting function, token buckets, etc. These traffic policy functions assure that individual traffic flows within the portion of each traffic type do not negatively interfere with each other. This allows us to consider elastic traffic and circuit-switched traffic separately and to determine their necessary capacity shares independently with different dimensioning models: for circuit- switched traffic the dimensioning models use Erlang-B formula or Multi-dimensional Erlang- B formula (as presented in section 6.2); whereas for elastic traffic the dimensioning models are based on M/G/R-PS model. In order to obtain the total capacity of the lub link Club, the individual bandwidth shares need to be summed up = Comparing these two dimensioning approaches, the latter achieves lower utilization as it does not achieve any multiplexing gain by using bandwidth portioning. In case of complete sharing the bandwidth among the two traffic types, multiplexing gain is attained and thus achievable utilization is higher. In the framework of this thesis, the elastic traffic completely shares the bandwidth with the circuit-switched traffic, and thus the first dimensioning approach is consid