Usage-Monitoring and reporting refers to the collection and reporting of octets (volume) that a service or application on the node has consumed during a specific period. The usage on the node is reported via the Gx interface to the PCRF. Based on this information, the PCRF can apply a specific action (policy change) to the entity being monitored. For example, QoS can be modified, or the service can be blocked when specific thresholds are reached.
Usage-Monitoring and reporting is performed over a single Gx session for the ESM/AA subscriber. In other words, there is only a single session for an ESM subscriber-host and corresponding AA subscriber. Via this single Gx session, Usage-Monitoring can be requested simultaneously in ESM context (PCC rule level, credit-category or IP-CAN session) and AA context (application based Usage-Monitoring).
For volume based usage monitoring in dual-homed system, see Gx Usage Monitoring in dual-homed systems.