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SRC 3GPP Gateway Overview

The SRC Third-Generation Partnership Project (3GPP) gateway is a Diameter-based component in the SRC software, which provides integration with 3GPP Policy and Charging Control environments, to provide fixed-mobile convergence (FMC).

The SRC 3GPP gateway provides Gx-based integration with the Policy and Charging Rules Function (PCRF). The SRC 3GPP gateway uses the Gx interface to mediate between the PCRF and Juniper Networks routers like the E Series Broadband Services routers and MX Series routers. Figure 1 shows an example network configuration where the SRC 3GPP gateway acts as a mediator between the PCRF and an MX Series router. The Gx interface on the SRC 3GPP gateway communicates with the PCRF using the Diameter protocol.

Figure 1: SRC 3GPP Gateway as a Mediator Between the PCRF and an MX Series Router

SRC 3GPP Gateway as a Mediator
Between the PCRF and an MX Series Router

Figure 2 represents the different policy references interfaces you can use, when using the SRC 3GPP gateway with other Juniper Networks products.

Figure 2: Various Interfaces on Juniper Networks Products Communicating with a PCRF Through the SRC 3GPP Gateway

Various Interfaces on
Juniper Networks Products Communicating with a PCRF Through the SRC
3GPP Gateway

The SRC 3GPP gateway supports the following scenarios:

The following sections describe the sequences for each of these scenarios based on using an MX Series router.

Subscriber Login Sequence

The subscriber login uses the following sequence:

  1. A subscriber session logs in and notifies the JSRC within the MX Series router.
  2. The MX Series router sends a Diameter AA-Request (AAR) for the new subscriber session.
  3. The service activation engine (SAE) performs necessary tasks such as creating the user session, provisioning any policy objects, and others.
  4. When the login is complete, the SAE sends back a Diameter AA-Answer (AAA) to the router.
  5. The SAE notifies the SRC 3GPP gateway that a subscriber was logged in successfully. This notification includes information such as the IP Address of the subscriber.
  6. The SRC 3GPP gateway sends a Diameter Credit-Control-Request (CCR) with the following information to the PCRF:
    • CC-Request-Type AVP: INITIAL_REQUEST
    • Framed-IP-Address AVP: user equipment IPv4 address or Framed-IPv6-Prefix AVP: user equipment IPv6 address
    • Subscription-Id AVP: the login-name SAE plug-in attribute (Subscription-Id-Type set to END_USER_E164(0)) and, if available, the interface description SAE plug-in attribute (Subscription-Id-Type set to END_USER_PRIVATE(4))
    • CalledStationId AVP: Set to virtual router name.

    The SRC 3GPP gateway selects the PCRF according to the referenced Diameter peers under the [edit slot 0 gw-3gpp gx diameter-peer] hierarchy.

  7. The SRC 3GPP gateway receives the Credit-Control-Answer (CCA) message from the PCRF.
    • If the PCRF rejected the CCR-I (initial) by providing an error code in the CCA message, the SRC 3GPP gateway logs the subscriber out using the SAE Common Object Request Broker Architecture (CORBA) interface.
    • If the PCRF accepted the CCR-I, the SRC 3GPP gateway iterates over the provided policy and charging control (PCC) rules (if any) from the CCA message and issues service activate calls for those services.
  8. The SRC 3GPP gateway iterates over PPC Rules from the CCA message and issues service activate calls for those services, if applicable.
  9. For each service to be activated, the SAE issues a Diameter Push-Profile-Request (PPR) to the MX Series router.
  10. The MX Series router sends an acknowledgment to the SAE in a Push-Profile-Answer (PPA) message.
  11. The SAE sends an acknowledgement to the SRC 3GPP gateway.

    The SRC 3GPP gateway collects all the failed service activations and sends a CCR-U (update) to the PCRF to indicate the failure. The SRC 3GPP gateway sets the experimental result code in the CCR-U to DIAMETER_PCC_RULE_EVENT(5142) and includes a charging-rule-report for each failed activation including the rule-name and the rule-failure-code.

Subscriber Logout Sequence

The subscriber logout uses the following sequence:

  1. A subscriber session logs out and notifies the JSRC within the MX Series router.
  2. The router sends a Diameter Session-Termination-Request (STR) to the SAE to indicate that the subscriber has logged out.
  3. The SAE notifies the SRC 3GPP gateway that the service session has stopped.

    For each service stop event, the SRC 3GPP gateway issues a CC-Request to the PCRF that includes:

    • CC-Request-Type AVP: UPDATE_REQUEST
    • Usage-Monitoring-Information AVP includes:
      • Final accounting data
  4. The SAE notifies the SRC 3GPP gateway that the subscriber was logged out successfully. The notification includes one of the following addresses:
    • Framed-IP-Address AVP: user equipment IPv4 address
    • Framed-IPv6-Prefix AVP: user equipment IPv6 address
  5. The SRC 3GPP gateway sends a Diameter CCR message with the following information to the PCRF:
    • CC-Request-Type AVP: TERMINATION_REQUEST
    • Subscriber-Id AVP includes one of the following addresses:
      • Framed-IP-Address AVP: user equipment IPv4 address
      • Framed-IPv6-Prefix AVP: user equipment IPv6 address
  6. The SRC 3GPP gateway receives the CCA message from the PCRF.
  7. The SAE acknowledges the STR sent by the router by sending a Session-Termination-Answer (STA) to the router.

Subscriber Session Termination Sequence (Initiated by PCRF)

When the PCRF initiates the subscriber session termination, the following sequence occurs:

  1. The application function requests the termination of the session from the PCRF.
  2. The PCRF issues a Re-Auth-Request (RAR) message, which includes the Session-Release-Cause AVP.
  3. The SRC 3GPP gateway issues a subscriber disconnect CORBA Call to the SAE. This method is not supported for JunosE Point-to-Point Protocol (PPP) sessions; in that case, the SRC 3GPP gateway only logs the subscriber out.
  4. The SAE performs the necessary steps to disconnect the subscriber. For JunosE PPP sessions, the subscriber is logged out using the subscriber logout procedure.
  5. The user equipment is disconnected.
  6. The router sends an acknowledgement to the SAE.
  7. The SAE acknowledges the CORBA Call by sending an acknowledgement to the SRC 3GPP gateway.
  8. The SRC 3GPP gateway acknowledges the RAR message sent by the PCRF by sending a Re-Auth-Answer (RAA) message to the PCRF.
  9. The SAE sends a Subscriber Stop Event message to the SRC 3GPP gateway.
  10. The SRC 3GPP gateway sends a CCR with the following information to the PCRF:
    • CC-Request-Type AVP: TERMINATION_REQUEST
    • Subscriber-Id AVP includes one of the following addresses:
      • Framed-IP-Address AVP: user equipment IPv4 address
      • Framed-IPv6-Prefix AVP: user equipment IPv6 address
  11. The SRC 3GPP gateway receives the CCA message.

Service Activation Sequence (Initiated by Application Function)

When the application function (AF) initiates a service activation, the following sequence occurs:

  1. The AF receives any kind of trigger to set up a new AF session and issues an AAR message to the PCRF.
  2. The PCRF stores all received service information, retrieves profiles, and sends an AA-Answer (AAA) message back to the AF.
  3. The PCRF issues an RAR message, with the Charging-Rule-Install AVP set.
  4. The SRC 3GPP gateway issues a subscriber activate service session CORBA Call to the SAE, by using the Bearer-Identity AVP (subscriber’s IP address) and service name (Charging-Rule-Name AVP).
  5. The SAE performs the necessary steps to activate the specified service for the given subscriber, including sending a Push-Profile-Request (PPR) message to the router.
  6. The router sends an acknowledgement (PPA) to the SAE.
  7. The SAE acknowledges the CORBA Call by sending an acknowledgement to the SRC 3GPP gateway.
  8. The SRC 3GPP gateway sends an Re-Auth-Answer (RAA) message to the PCRF.
  9. The SAE sends Service Start Event to the SRC 3GPP gateway.

Service Modification Sequence (Initiated by Application Function)

When the application function (AF) initiates a service modification, the following sequence occurs:

  1. The AF receives any kind of trigger to update an existing AF session and issues an AAR message to the PCRF.
  2. The PCRF stores all received service information, retrieves profiles, and sends an AA-Answer (AAA) message back to the AF.
  3. The PCRF issues an RAR message, with the Charging-Rule-Install AVP set.
  4. The SRC 3GPP gateway issues a subscriber-modify service CORBA Call to the SAE, which includes the subscriber IP address and the service name (Charging-Rule-Name AVP).
  5. The SAE performs the necessary steps to modify the specified service for the given subscriber, including sending a Push-Profile-Request (PPR) message to the router.
  6. The router sends an acknowledgement (PPA) to the SAE.
  7. The SAE acknowledges the CORBA Call by sending an acknowledgement to the SRC 3GPP gateway.
  8. The SRC 3GPP gateway sends a Re-Auth-Answer (RAA) message to the PCRF.

Service Deactivation Sequence (Initiated by Application Function)

When the application function (AF) initiates a service deactivation, the following sequence occurs:

  1. The AF receives any kind of trigger to terminate or deactivate an existing session and issues an AAR message to the PCRF.
  2. The PCRF stores all received service information, retrieves profiles, and sends an AA-Answer (AAA) message back to the AF.
  3. The PCRF issues an RAR message with the Charging-Rule-Remove AVP set.
  4. The SRC 3GPP gateway issues a subscriber-deactivate service CORBA Call to the SAE.
  5. The SAE performs the necessary steps to deactivate the specified service for the given subscriber, including sending a Push-Profile-Request (PPR) message to the router.
  6. The router sends an acknowledgement Push-Profile-Answer (PPA) to the SAE.
  7. The SAE acknowledges the CORBA Call by sending an acknowledgement to the SRC 3GPP gateway.
  8. The SRC 3GPP gateway sends a Re-Auth-Answer (RAA) message to the PCRF.
  9. The SAE sends a Service Stop Event to the SRC 3GPP gateway. The SRC 3GPP gateway issues a CCR to the PCRF including:
    • CC-Request-Type AVP: UPDATE_REQUEST
    • Usage-Monitoring-Information AVP includes:
      • Final accounting data

Published: 2014-06-12