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Gx Interface Support
Step
Description
6
DPCA sends a CCR initial message to the selected PCRF. This message includes the Context-Type AVP set to PRIMARY
and the IP address allocated to the UE. The message may include the Bearer-Usage AVP set to GENERAL. The Bearer-
Operation is set to Establishment. The Bearer ID is included if the PCRF does the bearer binding.
7
PCRF may send preconfigured charging rules in CCA, if a preconfigured rule set for general purpose PDP context is
provided in PCRF. The dynamic rules and the authorized QoS parameters could also be included by the PCRF.
8
DPCA passes the charging rule definition, charging rule install, QoS information received from the PCRF, event triggers,
and so on, along with the Bearer ID that corresponds to the rules received from the PCRF to IMSA. IMSA stores the
information. If the Bearer ID is absent, and PCRF does the bearer binding, the rule is skipped. Whereas, if the Bearer ID is
absent and the PCEF does the bearer binding, the rule is passed onto the ECS to perform bearer binding.
9
DPCA calls the callback function registered with it by IMSA.
10
IMSA stores the bearer authorized QoS information and notifies the SessMgr. Other PCRF provided information common
to the entire PDP session (event trigger, primary/secondary OCS address, and so on) is stored within the IMSA. After
processing the information, IMSA notifies the SessMgr about the policy authorization complete.
11
If the validation of the rules fails in IMSA/DPCA, a failure is notified to PCRF containing the Charging-Rule-Report AVP.
Else, IMSA initiates creation of ECS session. The APN name, primary/secondary OCS server address, and so on are sent to
the ECS from the SessMgr.
12
ECS performs credit authorization by sending CCR(I) to OCS with CC-Request-Type set to INITIAL_REQUEST to open
the credit control session. This request includes the active Rulebase-Id (default rulebase ID from the APN/AAA) and GPRS
specific attributes (for example, APN, UMTS QoS, and so on).
13
OCS returns a CCA initial message that may activate a statically configured Rulebase and may include preemptive quotas.
14
ECS responds to SessMgr with the response message.
15
SessMgr requests IMSA for the dynamic rules.
16
IMSA sends the dynamic rules to SessMgr.
Note that, in 14.0 and later releases, the RAR messages are allowed before the session is established. In earlier releases,
until the primary PDP context is established, all RAR messages from the PCRF were rejected.
Also note that, in 14.0 and later releases, the RAR message is rejected and RAA is sent with 3002 result code when the
recovery of dynamic rule information and audit of Session Manager are in progress. Earlier, the RAR messages were
processed by DPCA even when the recovery audit was in progress.
17
SessMgr sends the dynamic rule information to the ECS. The gate flow status information and the QoS per flow (charging
rule) information are also sent in the message.
18
ECS activates the predefined rules received, and installs the dynamic rules received. Also, the gate flow status and the QoS
parameters are updated by ECS as per the dynamic charging rules. The Gx rulebase is treated as an ECS group-of-ruledefs.
The response message contains the Charging Rule Report conveying the status of the rule provisioning at the ECS. ECS
performs PCEF bearer binding for rules without bearer ID.
19
If the provisioning of rules fails partially, the context setup is accepted, and a new CCR-U is sent to the PCRF with the
Charging-Rule-Report containing the PCC rule status for the failed rules. If the provisioning of rules fails completely, the
context setup is rejected.
20
Depending on the response for the PDP Context Authorization, SessMgr sends the response to the UE and activates/rejects
the call. If the Charging-Rule-Report contains partial failure for any of the rules, the PCRF is notified, and the call is
activated. If the Charging-Rule-Report contains complete failure, the call is rejected.
21
Based on the PCEF bearer binding for the PCC rules at Step 18, the outcome could be one or more network-initiated PDP
context procedures with the UE (Network Requested Update PDP Context (NRUPC) / Network Requested Secondary PDP
Context Activation (NRSPCA)).
Cisco ASR 5x00 Packet Data Network Gateway Administration Guide ▄
Rel. 7 Gx Interface ▀
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