Section: 12.3.9.3.4 Based on the Message Priority signalled in the GTP-C message
Content: Message prioritization may be performed by an overloaded node, when handling incoming messages during an overloaded condition, based on the relative GTP-C message priority signalled in the GTP-C header (see clauses 5.4 and 5.5). A GTP-C entity shall determine whether to set and use the message priority in GTP-C signalling within the PLMN and/or across the PLMN boundaries, based on operator policy and roaming agreements. The following requirements shall apply if being used. A sending GTP-C entity shall determine the relative message priority to signal in the message according to the principles specified in clause 12.3.9.3.1. If the message affects multiple bearers (e.g. Modify Bearer Request), the relative message priority should be determined considering the highest priority ARP among all the bearers. A GTP-C entity should set the same message priority in a Triggered message or Triggered Reply message as received in the corresponding Initial message or Triggered message respectively. The message priority values sent on intra-network interfaces may differ from the values sent on inter-network interfaces. When messages cross PLMN boundaries, the Message Priority in the GTP-C header may be stripped or modified in these messages. NOTE : This is to take into account that the priority definitions can vary between PLMNs and avoid messages from a foreign PLMN to gain unwarranted preferential treatment. For incoming GTP-C messages that do not have a message priority in the GTP-C header, the receiving GTP-C entity: - shall apply a default priority, if the incoming message is an Initial message; - should apply the message priority sent in the Initial message or Triggered message, if the incoming message is a Triggered or Triggered Reply message (respectively). This feature should be supported homogenously across the nodes in the network, otherwise an overloaded node will process initial messages received from the non-supporting nodes according to the default priority while initial messages received from supporting nodes will be processed according to the message priority signalled in the GTP-C message.