SRC 3GPP Gy Overview

The SRC 3GPP Gy feature is a Diameter-based component in the SRC software, which provides integration with the Online Charging System (OCS) to support fixed-mobile convergence (FMC).

SRC’s Gy uses the northbound Gy interface to handle charging-related information between the OCS and Juniper Networks routers like the E Series Broadband Services routers and MX Series routers. Figure 1 shows an SRC 3GPP Gy deployment scenario. The northbound Gy interface on SRC’s Gy communicates with the OCS using the Diameter protocol.

Note: SRC’s Gy supports volume-based quota only.

Figure 1: SRC 3GPP Gy Deployment Scenario

Subscriber Login Sequence

During subscriber login, the SAE notifies a service authorization event to SRC’s Gy for each service to be activated. This event includes information such as login name, service name, session handle, service identifier, and other SAE plug-in attributes.

SRC’s Gy performs the following actions for service activation received through activate-on-login (AOL) or SRC 3GPP gateway:

1. Sends a Diameter Credit-Control-Request initial (CCR-I) message with the following information to the OCS:
   • CC-Request-Type AVP: INITIAL_REQUEST
   • Subscription-ID AVP: Login name received from the router as an SAE plug-in attribute
   • Service-Identifier AVP: Identifier of the service. This AVP is available in the message only if the identifier is configured for the service.

     Note: Gy functionalities require service identifier information, so you must ensure that the identifier is configured for the service.

   • Multiple-Service-Credit-Control AVP: Grouped AVP that contains:
     • Requested-Service-Unit AVP: Grouped AVP that contains:
       • CC-Input-Octets AVP: Value is always set to zero
       • CC-Output-Octets AVP: Value is always set to zero
       • CC-Total-Octets AVP: Value is always set to zero
2. Receives the Credit-Control-Answer initial (CCA-I) message from the OCS.
   • If the OCS rejected the CCR-I message by providing an error code in the CCA-I message, SRC’s Gy requests the SAE not to activate the service for the subscriber.
   • If the OCS accepted the CCR-I message, SRC’s Gy requests the SAE to activate the service for the subscriber and saves the received quota information in the service session properties. SAE interacts with the router to activate the service for the subscriber.

   The CCA-I message contains the following information:

   • CC-Request-Type AVP: INITIAL_REQUEST
   • Subscription-ID AVP: Login name received from the router as an SAE plug-in attribute
   • Multiple-Service-Credit-Control AVP: Grouped AVP that contains:
     • Granted-Service-Unit AVP: Grouped AVP that contains:
       • CC-Total-Octets AVP: The number of octets that can be received and sent by the router
       • CC-Input-Octets AVP: The number of octets that can be received by the router from the subscriber
       • CC-Output-Octets AVP: The number of octets that can be sent from the router to the subscriber
       • Final-Unit-Indication AVP: Indicates that the Granted-Service-Unit AVP has final units for the service
       • Volume-Quota-Threshold AVP: Threshold value in octets

Subscriber Logout Sequence

During subscriber logout, the SAE notifies a service stop event to SRC’s Gy for each active service. The event contains accounting statistics received from the router.

For each service stop event, SRC’s Gy issues a CCR termination (CCR-T) message to the OCS that includes:

• CC-Request-Type AVP: TERMINATION_REQUEST
• Subscription-ID AVP: Login name received from the router as an SAE plug-in attribute
• Service-Identifier AVP: Identifier of the service. This AVP is available in the message only if the identifier is configured for the service.

  Note: Gy functionalities require service identifier information, so you must ensure that the identifier is configured for the service.

• Multiple-Service-Credit-Control AVP: Grouped AVP that contains:
  • Used-Service-Unit AVP: Grouped AVP that contains:
    • CC-Input-Octets AVP: The number of octets received by the router from the subscriber
    • CC-Output-Octets AVP: The number of octets sent from the router to the subscriber
    • CC-Total-Octets AVP: The number of octets received and sent by the router
    • Terminate-Cause AVP: Reason for terminating the service. The value is set to USER_REQUEST.

Service Activation Sequence

When the Application Function (AF), Dynamic Service Activator (DSA), AOL, scheduler, or Volume Tracking Application (VTA) initiates a service activation, the SAE triggers a service authorization event to SRC’s Gy. The event includes information such as login name, service name, session handle, service identifier, and other SAE plug-in attributes. SRC’s Gy performs the following actions:

1. Sends a Diameter CCR-I message with the following information to the OCS:
   • CC-Request-Type AVP: INITIAL_REQUEST
   • Subscription-ID AVP: Login name received from the router as an SAE plug-in attribute
   • Service-Identifier AVP: Identifier of the service. This AVP is available in the message only if the identifier is configured for the service.

     Note: Gy functionalities require service identifier information, so you must ensure that the identifier is configured for the service.

   • Multiple-Service-Credit-Control AVP: Grouped AVP that contains:
     • Requested-Service-Unit AVP: Grouped AVP that contains:
       • CC-Input-Octets AVP: Value is always set to zero
       • CC-Output-Octets AVP: Value is always set to zero
       • CC-Total-Octets AVP: Value is always set to zero
2. Receives the CCA message from the OCS.
   • If the OCS rejected the CCR-I message by providing an error code in the CCA message, SRC’s Gy requests the SAE not to activate the service for the subscriber.
   • If the OCS accepted the CCR-I message, SRC’s Gy requests the SAE to activate the service for the subscriber and saves the received quota information in the service session properties. SAE interacts with the router to activate the service for the subscriber.

   The CCA-I message contains the following information:

   • CC-Request-Type AVP: INITIAL_REQUEST
   • Subscription-ID AVP: Login name received from the router as an SAE plug-in attribute
   • Multiple-Service-Credit-Control AVP: Grouped AVP that contains:
     • Granted-Service-Unit AVP: Grouped AVP that contains:
       • CC-Total-Octets AVP: The number of octets that can be received and sent by the router
       • CC-Input-Octets AVP: The number of octets that can be received by the router from the subscriber
       • CC-Output-Octets AVP: The number of octets that can be sent from the router to the subscriber
       • Final-Unit-Indication AVP: Indicates that the Granted-Service-Unit AVP has final units for the service
       • Volume-Quota-Threshold AVP: Threshold value in octets

Service Deactivation Sequence

When the AF, DSA, AOL, scheduler, or VTA initiates a service deactivation, the SAE triggers a service stop event to SRC’s Gy. The event contains accounting statistics received from the router.

SRC’s Gy issues a CCR-T message to the OCS that includes:

• CC-Request-Type AVP: TERMINATION_REQUEST
• Subscription-ID AVP: Login name received from the router as an SAE plug-in attribute
• Service-Identifier AVP: Identifier of the service. This AVP is available in the message only if the identifier is configured for the service.

  Note: Gy functionalities require service identifier information, so you must ensure that the identifier is configured for the service.

• Multiple-Service-Credit-Control AVP: Grouped AVP that contains:
  • Used-Service-Unit AVP: Grouped AVP that contains:
    • CC-Input-Octets AVP: The number of octets received by the router from the subscriber
    • CC-Output-Octets AVP: The number of octets sent from the router to the subscriber
    • CC-Total-Octets AVP: The number of octets received and sent by the router
    • Terminate-Cause AVP: Reason for terminating the service. The value is set to USER_REQUEST.

Service Accounting Sequence

After the service is activated by the SAE, the following sequences occur:

1. The SAE updates SRC’s Gy with the used service units received from the router through accounting messages.
2. SRC’s Gy tracks the quota or threshold usage with the information received from the OCS.
3. If the quota or threshold is exhausted, SRC’s Gy sends a CCR update (CCR-U) message to the OCS with the following information to request for a new quota:
   • CC-Request-Type AVP: UPDATE_REQUEST
   • Subscription-ID AVP: Login name received from the router as an SAE plug-in attribute
   • Service-Identifier AVP: Identifier of the service. This AVP is available in the message only if the identifier is configured for the service.

     Note: Gy functionalities require service identifier information, so you must ensure that the identifier is configured for the service.

   • Multiple-Service-Credit-Control AVP: Grouped AVP that contains:
     • Requested-Service-Unit AVP: Grouped AVP that contains:
       • CC-Input-Octets AVP: Value is always set to zero
       • CC-Output-Octets AVP: Value is always set to zero
       • CC-Total-Octets AVP: Value is always set to zero
     • Used-Service-Unit AVP: Grouped AVP that contains:
       • CC-Input-Octets AVP: The number of octets received by the router from the subscriber
       • CC-Output-Octets AVP: The number of octets sent from the router to the subscriber
       • CC-Total-Octets AVP: The number of octets received and sent by the router
       • Reporting-Reason AVP: Reason for usage reporting. The value is set to QUOTA_EXHAUSTED, if the granted quota in the Granted-Service-Unit AVP is exhausted. The value is set to THRESHOLD, if the granted quota in Volume-Quota-Threshold AVP is exhausted.
4. The OCS sends the CCA update (CCA-U) message to SRC’s Gy with the following information:
   • CC-Request-Type AVP: UPDATE_REQUEST
   • Subscription-ID AVP: Login name received from the router as an SAE plug-in attribute
   • Multiple-Service-Credit-Control AVP: Grouped AVP that contains:
     • Granted-Service-Unit AVP: Grouped AVP that contains:
       • CC-Total-Octets AVP: The number of octets that can be received and sent by the router
       • CC-Input-Octets AVP: The number of octets that can be received by the router from the subscriber
       • CC-Output-Octets AVP: The number of octets that can be sent from the router to the subscriber
       • Final-Unit-Indication AVP: Indicates that the Granted-Service-Unit AVP has final units for the service
       • Volume-Quota-Threshold AVP: Threshold value in octets
5. SRC’s Gy stores the quota in the service session properties.
6. The SAE updates SRC’s Gy with the used service units received from the router through accounting messages.
7. SRC’s Gy checks whether the Final-Unit-Indication AVP is stored in the service session properties. If the Final-Unit-Indication AVP is available, SRC’s Gy requests SAE to deactivate the service. For more information about the communication between SRC’s Gy and OCS during service deactivation, see Service Deactivation Sequence.
8. If the Final-Unit-Indication AVP is not available, SRC’s Gy iterates sending of CCR-U messages to the OCS to request for a new quota.