Section: 12.2.4.3 Elements of APN load control
Content: To allow for an effective APN load control, at least the following information (in addition to the other applicable information for load control as defined in clause 12.2.5.1.2) is required to be advertised by the PGW, as part of the APN level load information: APN: The APN for which the PGW wants to advertise the load information. APN-Load-Metric: It indicates the current resource utilization for a particular APN, as a percentage, compared to the total resources reserved for that APN at the target PGW. Its computation is implementation dependent and it has same characteristics as "Load-Metric", as described in clause 12.2.5.1.2.2, when applied at the APN level. APN-relative-capacity: It indicates the total resources configured for a given APN, compared to the total resources of the target PGW, as a percentage. It is a static parameter and does not change unless the resources configured for the APN change. Using APN-relative-capacity and the DNS weight-factor of the given PGW, the source node can judge the PGW's APN related resources as compared other PGWs in the network, i.e. the PGW's APN-weight-factor can be calculated by multiplying the APN-relative-capacity and DNS-weight-factor of the PGW (PGW's-APN-weight-factor = PGW's-APN-relative-capacity X DNS-weight-factor). For the following example configuration: PGW1-APN1-relative-capacity = 50%; PGW2-APN1- relative-capacity = 20%; PGW3-APN1- relative-capacity = 10% PGW1-weight-factor = 20; PGW2-weight-factor = 20; PGW3-weight-factor = 60; The APN level weight-factor for each of the PGWs can be calculated as below: PGW1-APN1-weight-factor = 50% X 20 = 10. PGW2-APN1-weight-factor = 20% X 20 = 4. PGW3-APN1-weight-factor = 10% X 60 = 6. Thus, based on the APN-weight-factor it can be concluded that the PGW1 has highest APN1 related resources reserved, as compared to the other PGWs in the network. Hence the source node should use this information to favour PGW1 over other PGWs for APN1 related new session requests.