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SAE Support for Gx Router Driver

 

The SAE performs the following actions using the Gx router driver of the SRC software acting as a policy and charging rule function (PCRF):

  • Provides solicited or unsolicited provisioning of Policy and Charging Control (PCC) rules or enhanced PCC (ePCC) rules to the MX Series routers (that is, Services Control Gateway) acting as a policy and charging enforcement function (PCEF).

  • Handles traffic plane event received from the Services Control Gateway.

  • Removes the provisioned PCC or ePCC rules.

  • Monitors service usage for the subscriber.

You can use multiple SAEs (that is, multiple SRC softwares) to manage the same Services Control Gateway. In this scenario, the SAEs elect an active instance of the Gx router driver to manage the Services Control Gateway.

Subscriber Session Creation

The subscriber session creation sequence is as follows:

  1. The Services Control Gateway sends a request message (Credit-Control-Request initial (CCR-I)) to the Diameter server of the SRC software. This message contains Subscription-Id and Auth-Application-Id AVPs.

    In the SRC software, the Subscription-Id AVP is mapped to the login-name attribute. When multiple Subscription-Id AVPs are received, the first received identifier is mapped to the login-name attribute.

  2. The Diameter server checks whether the Auth-Application-Id AVP in the request message denotes the Gx application identifier. If the Auth-Application-Id AVP is not valid, the Diameter server sends an error response to the Services Control Gateway.

  3. If the Auth-Application-Id AVP is valid, the Diameter server checks whether a corresponding Gx router driver is registered with the Diameter server. If no Gx router driver is registered, the Diameter server sends an error response to the Services Control Gateway.

  4. If a registered Gx router driver is available, the Diameter server delegates the request message to the SAE as a Common Object Request Broker Architecture (CORBA) request.

  5. The SAE performs interface classification (if configured) and then performs subscriber classification based on the Subscription-Id AVP received in the request message. If there is no subscriber classification available for the subscriber, the SAE classifies the subscriber as an unauthenticated user profile.

  6. If the subscriber classification is successful, the SAE creates a user session for the subscriber and activates the activate-on-login subscriptions configured for the subscriber. Then, the SAE associates corresponding PCC or ePCC rules to the service based on the configuration.

  7. The SAE sends a success response message (Credit-Control-Answer initial (CCA-I)) with the provisioned rules to the Diameter server that delegates the response message to the Services Control Gateway.

  8. The Services Control Gateway applies the provisioned rules to the subscriber.

Subscriber Session Updation

The subscriber session updation sequence is as follows:

  1. The Services Control Gateway sends a request message (CCR update (CCR-U)) to the Diameter server of the SRC software. This message contains Session-Id and Auth-Application-Id AVPs.

  2. The Diameter server checks whether the Auth-Application-Id AVP in the request message denotes the Gx application identifier. If the Auth-Application-Id AVP is not valid, the Diameter server sends an error response to the Services Control Gateway.

  3. If the Auth-Application-Id AVP is valid, the Diameter server checks whether a corresponding Gx router driver is registered with the Diameter server. If no Gx router driver is registered, the Diameter server sends an error response to the Services Control Gateway.

  4. If a registered Gx router driver is available, the Diameter server delegates the request message to the SAE as a CORBA request.

  5. The SAE searches for the subscriber session using the Session-Id AVP. If no matching session is available, the SAE sends an error response to the Services Control Gateway.

  6. If a matching session is identified, the SAE performs the following actions:

    • Updates the session with the information received in the request message.

    • Notifies the SAE plug-ins about the event that triggered the request message.

    • Publishes the received information to the SAE plug-ins.

    • Triggers a Re-Auth-Request (RAR) message with Charging-Rule-Install AVP or Charging-Rule-Remove AVP only when you invoke the Dynamic Service Activator (DSA) portal APIs or SAE core APIs.

  7. The SAE sends a success response message (CCA update (CCA-U)) to the Diameter server that delegates the response message to the Services Control Gateway as an acknowledgement.

    If the AutoDeactivateOnThreshold flag is enabled at service level configuration and the usage monitoring threshold is reached, the SAE sends the Charging-Rule-Remove AVP in the response message (CCA-U).

Subscriber Session Reauthorization

The subscriber session reauthorization sequence is as follows:

  1. The SAE retrieves the subscriber session if the subscription change request message is received from the DSA or SAE CORBA API, any policy parameter is changed, or any subscription is changed for the subscriber profile.

  2. The SAE rebuilds the provisioning set based on the configured rules and updates the profile.

  3. The SAE constructs a RAR message with Charging-Rule-Remove AVP or Charging-Rule-Install AVP based on the policy changes, subscription changes, service activation, and service deactivation.

  4. The SAE sends the RAR messages to the Diameter server that delegates the RAR message to the Services Control Gateway.

  5. The Services Control Gateway acknowledges the RAR message by sending the Re-Auth-Answer (RAA) message.

Note

SRC software does not send the RAR message to the Services Control Gateway when the 3GPP attributes are modified at the subscriber level or service level for the logged in subscribers.

Subscriber Session Detach

The subscriber session detach sequence is as follows:

  1. The Services Control Gateway sends a request message (CCR termination (CCR-T)) to the Diameter server of the SRC software.

  2. The Diameter server delegates the request message to the SAE as a CORBA request.

  3. The SAE searches for the subscriber session using the Session-Id AVP. If no matching session is available, the SAE sends an error response to the Services Control Gateway.

  4. If a matching session is identified, the SAE performs the following actions:

    • Deletes the session details from the SAE user manager.

    • Publishes the subscriber and service tracking stop events to the SAE plug-ins.

    • Updates the subscriber session detach information in the session store.

  5. The SAE sends a response message (CCA termination (CCA-T)) to the Diameter server that delegates the response message to the Services Control Gateway.

Service Accounting

You can perform service accounting for one or more PCC or ePCC rules.

When a SRC software requests service accounting, the SRC software should configure the Event-Trigger AVP to USAGE_REPORT and also should enable the accounting flag for at least one policy rule for a service. SRC software must send the Usage-Monitoring-Information AVP either in the RAR message (if the SRC software initiates the rule changes) or the CCA message.

The SRC software provides usage threshold levels to the Services Control Gateway during session establishment (CCA or RAR message). This is done, by setting a usage monitoring threshold in the grouped Granted-Service-Unit AVP per Monitoring-Key in the Usage-Monitoring-Information AVP. The threshold level may be defined for:

  • Total volume only (CC-Total-Octets AVP within Granted-Service-Unit hold threshold for total volume)

  • Uplink volume only (CC-Input-Octets AVP within Granted-Service-Unit hold threshold for uplink volume)

  • Downlink volume only (CC-Output-Octets AVP within Granted-Service-Unit hold threshold for downlink volume)

  • Both uplink and downlink volume (CC-Input-Octets and CC-Output-Octets AVPs within Granted-Service-Unit)

The Services Control Gateway sends the accounting updates by setting the usage counters in the Used-Service-Unit AVP within the Usage-Monitoring-Information AVP. Like the Granted-Service-Unit AVP (for setting the threshold), the Used-Service-Unit AVP is a grouped AVP and the Services Control Gateway uses the CC-Total-Octet, CC-Input-Octets, and CC-Output-Octets AVP within the Used-Service-Unit AVP to report the service usage to the SRC software. The Services Control Gateway sends the accounting updates only in CCR-U or CCR-T message (not in RAA message).

The Services Control Gateway reports the used service units when any of the following conditions are met:

  • Usage threshold is reached.

  • Service is deactivated (the PCC or ePCC rule, for which service accounting is enabled, is removed).

  • Service accounting is explicitly disabled by the SRC software for a specific PCC or ePCC rule.

  • IP-CAN session is terminated (either by the SRC software through the RAR message, or initiated by the Services Control Gateway).

  • SRC software requested the Services Control Gateway to share the accounting update.

Note

The SRC software does not support interim accounting interval configuration for the Gx router driver.

SAE Plug-In Attributes

When the Gx router driver is used to manage the Services Control Gateway, the SAE publishes the event-trigger information ( such as APPLICATION_START, APPLICATION_STOP, and USAGE_REPORT) to the plug-ins on receiving a CCR-U message from the Services Control Gateway.

The SAE publishes the usage monitoring information to the plug-ins on receiving the CCR-T message from the Services Control Gateway. Table 3 lists the plug-in attributes used by the SAE to publish event-trigger and usage monitoring information.

Table 3: Plug-In Attributes Used by SAE to Publish Event-Trigger and Usage Monitoring Information

Plug-in Attributes

Description

Supported Plug-in Type

PA_RATING_GROUP

Rating group identifier. Services of same rating type are managed through the same rating group.

  • Service Authorization Plug-in

  • Service Tracking Plug-in

PA_SERVICE_IDENTIFIER

Service identifier or service configuration.

  • Service Authorization Plug-in

  • Service Tracking Plug-in

PA_EVENT_TRIGGER

Event type (such as APPLICATION_START and APPLICATION_STOP).

User Tracking Plug-in

PA_TDF_APP_ID

Identifier representing an application in which Application Detection and Control (ADC) rule is applied.

User Tracking Plug-in

PA_TDF_APP_INSTANCE_ID

Application instance identifier dynamically assigned by the Services Control Gateway.

User Tracking Plug-in

PA_TOTAL_OCTETS

Total bandwidth (uplink and downlink) consumed by the subscriber.

  • User Tracking Plug-in

  • Service Tracking Plug-in