lan. However, there are additional limitations, which may not be SO obvious at a first glance, directly related to the traffic profile. Mobility management and session management procedures are two of the most important functionalities provided by the SGSN. Session management limitations normally arise from the amount of simultaneous PDP context active in the SGSN. In terms of mobility management, the most obvious limitation comes from the maximum amount of subscribers simultaneously attached to the given SGSN. Therefore, the two main capacity related constraints in terms of subscribers are the maximum amount of simultaneous PDP contexts and the maximum amount of subscribers simultaneously attached. Thus, it is important to obtain from the vendor product documentation of those limits, SO as to ensure that the expected subscribers and their traffic can have a proper fit. In particular, the possibility should be considered of a subscriber having more than one PDP context active simultaneously. Additional possible constraints may come in the form of routing area update (RAU) procedures. The SGSN may have additional limitations from the maximum amount of procedures that can be handled in a given time, and they should be checked, especially if the input provided also specifies this type of requirement. Having all the limiting factors affecting the dimensioning of SGSN worked out and having decided upon the geographical strategy for core site deployment, it is the moment to bring up the final calculation for the number - and configuration type, in its case - of SGSN nodes to be deployed in a given core site in a given year. The procedure is actually quite straightforward, as described in the next steps. Firstly, consideration is given to all the expected Iu-PS interface traffic flows previously calculated that originate from all the RNCs expected to be homed into the core network site under study. The total Dimensioning amount of traffic, in megabits per second, is divided by the maximum throughput that one single SGSN