In the ESM context, volume consumption (octets - 3GPP 23.203 §4.4) can be monitored on three levels:
per entire IP-CAN session
per credit-category
per PCC rule
Usage-Monitoring can be monitored simultaneously on all three levels.
An IP-CAN session on the node represents a subscriber-host whose service types are determined by the sla-profile instance. In per IP-CAN session volume monitoring, the aggregated queue or policer counters are reported per direction (in or out). This includes dynamic policers that are instantiated as a result of a Gx action; for example, rate-limiting.
The following configuration is necessary to allow per IP-CAN session level Usage-Monitoring to be enabled for sessions associated with the category map:
configure
subscriber-mgmt
category-map <category-map-name> [create]
gx-session-level-usage
If the sla-profile instance changes mid-session, the counters are reset.
One obvious difference between regular RADIUS accounting and Gx Usage-Monitoring is that in RADIUS accounting the cumulative byte number for sla-profile instance is presented in each report (interim-updates or stop acct messages), while in Usage-Monitoring this count is reset between the two reports (when the quota is reached, the usage report is triggered).
Per credit-category monitoring refers to volume monitoring of a single queue/policer or a set of queues/policers within the sla-profile instance. Each queue/policer (or set of queues/policers as a subset of the sla-profile instance) represents a service for which the Usage-Monitoring is required. Those queues/policers (services) are organized on the node in credit categories.
*A:7750>config>subscr-mgmt>cat-map# info
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activity-threshold 1
credit-exhaust-threshold 50
category "queue1" create
queue 1 ingress-egress
exit
category "queue3-5" create
queue 3 ingress-egress
queue 5 ingress-egress
exit
category "rest-queues" create
queue 2 egress-only
queue 4 egress-only
queue 6 egress-only
queue 7 egress-only
queue 8 egress-only
exit
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Each service category has a name that is used to reference the category in Usage-Monitoring and reporting.
The category-map (predefined on the node) that is used in Usage-Monitoring can be associated with the subscriber-host through the following methods (in the order of priority):
PCRF — Charging-Rule-Install AVP that references the category map in Charging-Rule-Name = cat-map:<cat-map-name>
LUDB
RADIUS
Python script
PCC rule Usage-Monitoring reports volume usage per flow or set of flows. PCC rule Usage-Monitoring is described in a separate section below.
Usage-Monitoring for the subscriber host can be configured on the node, but it is not active until it is turned on by the PCRF either via CCA-i, CCA-u or RAR.
Usage-Monitoring can be enabled per ingress or egress direction or as total count. However monitoring the total count and per direction count are mutually exclusive. For example, total Usage-Monitoring cannot be enabled simultaneously with ingress (or egress) Usage-Monitoring for the same monitoring entity (session or category).