Gx Interface Support
▀ Rel. 7 Gx Interface
▄ Cisco ASR 5x00 Packet Data Network Gateway Administration Guide
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Feature Overview
The Volume Reporting over Gx feature provides PCRF the capability to make real-time decisions based on the data
usage by subscribers.
Important:
Volume Reporting over Gx is applicable only for volume quota.
Important:
In release 10.0, only total data usage reporting is supported, uplink/downlink level reporting is not
supported. In 10.2 and later releases, it is supported.
Important:
The PCEF only reports the accumulated usage since the last report for usage monitoring and not from
the beginning.
Important:
If the usage threshold is set to zero (infinite threshold), no further threshold events will be generated
by PCEF, but monitoring of usage will continue and be reported at the end of the session.
Important:
In 12.2 and later releases, usage reporting on bearer termination is supported.
The following steps explain how Volume Reporting over Gx works:
1.
PCEF after receiving the message from PCRF parses the usage monitoring related AVPs, and sends the
information to IMSA.
2.
IMSA updates the information to ECS.
3.
Once the ECS is updated with the usage monitoring information from PCRF, the PCEF (ECS) starts tracking the
data usage.
4.
For session-level monitoring, the ECS maintains the amount of data usage.
5.
For PCC rule monitoring, usage is monitored with the monitoring key as the unique identifier. Each node
maintains the usage information per monitoring key. When the data traffic is passed, the usage is checked
against the usage threshold values and reported as described in the
Usage Reporting
section.
6.
The PCEF continues to track data usage after the threshold is reached and before a new threshold is provided by
the PCRF. If a new usage threshold is not provided by the PCRF in the acknowledgement of an IP-CAN
Session modification where its usage was reported, then usage monitoring does not continue in the PCEF for
that IP CAN session.
Usage Monitoring
Usage Monitoring at Session Level: PCRF subscribes to the session-level volume reporting over Gx by sending
the Usage-Monitoring-Information AVP with the usage threshold level set in Granted-Service-Unit AVP and
Usage-Monitoring-Level AVP set to SESSION_LEVEL(0). After the AVPs are parsed by DPCA, IMSA
updates the information to ECS. Once ECS is updated usage monitoring is started and constantly checked with
the usage threshold whenever the data traffic is present. In 11.0 and later releases, Monitoring Key at session
level is supported.
In 12.0 and later releases, enabling and disabling session usage in a single message from PCRF is supported.
This is supported only if the monitoring key is associated at session level.
