3GPP-Based Diameter Credit Control Application (DCCA) - Online Charging

The 3GPP-based Diameter Credit Control Online Charging applications allow the control of subscriber access to services based on a pre-paid credit. The volume and time accounting on the node supports online charging using the Diameter Credit-Control Application (DCCA). The node supports Session Charging with Unit Reservation (SCUR), allowing the node to reserve volume and time quotas for rating-groups. Furthermore, the node supports centralized unit determination and centralized rating: it requests quotas and reports usage against the quota provided by the Online Charging Server (OCS). Credit control is always on a per-rating group basis. A rating group maps to a category inside a category map of the node volume-based and time-based accounting function.

The following are the basic configuration steps:

1. Configure a diameter policy.

   In the config>aaa CLI context, configure a Diameter peer policy with one or multiple Diameter peers.

   
   configure
       aaa
           diameter-peer-policy "diameter-peer-policy-1" create
               description "Diameter peer policy"
               applications gy
               connection-timer 5
               origin-host "bng.domain.com"
               origin-realm "domain.com"
               source-address 10.0.0.1
               peer "peer-1" create
                   address 10.1.0.1
                   destination-host "server.domain.com"
                   destination-realm "domain.com"
                   no shutdown
               exit
           exit
       exit
   
   

   When the diameter peer is reachable from IPv6, then the peer address should be specified as an IPv6 address. Optionally, an IPv6 source address can be specified:

   
   configure
       aaa
           diameter-peer-policy "diameter-peer-policy-1" create
               ---snip---
               ipv6-source-address 2001:db8::1
               peer "peer-1" create
                   address 2001:db8:100::1
                   ---snip---
   

2. Configure a diameter application policy.

   In the config>subscr-mgmt CLI context, configure a diameter application policy:

   1. Set the application to Gy (Diameter Credit Control Application)

   2. Specify the Diameter peer policy to use and optionally specific additional Gy application specific parameters (for example AVP format).

   
   configure
       subscriber-mgmt
           diameter-application-policy "diameter-gy-policy-1" create
               description "Diameter Gy policy"
               application gy
               diameter-peer-policy "diameter-peer-policy-1"
               gy
                   avp-subscription-id subscriber-id type e164
                   include-avp
                       radius-user-name
                   exit
               exit
           exit
       exit
   
   
   

3. Create a category-map and define:

   • the credit type (time or volume)

   • a category defining the queues to monitor for quota consumption and the rating-group this category maps to in DCCA

   
   configure
       subscriber-mgmt
           category-map "cat-map-1" create
               description "Category Map"
               credit-type time
               category "cat-1" create
                   rating-group 1
                   queue 1 ingress-egress
                   exhausted-credit-service-level
                       pir 256
                   exit
               exit
           exit
       exit
   
   

4. Create a credit control policy.

   Define the credit control servers to use by specifying the diameter application policy. Optionally, specify the default-category-map and an out-of-credit-action.

   
   configure
       subscriber-mgmt
           credit-control-policy "cc-policy-1" create
               description "Credit Control Policy"
               credit-control-server diameter "diameter-gy-policy-1"
               default-category-map "cat-map-1"
               out-of-credit-action change-service-level
           exit
       exit
   
   
   

5. Configure the diameter credit-control-policy in the sla-profile of the subscriber host for which credit control should be activated.

   
   configure
       subscriber-mgmt
           sla-profile "sla-profile-3" create
               description "SLA profile"
               credit-control-policy "cc-policy-1"
           exit
       exit
   
   
   

The following are examples of Diameter online charging flows:

• scenario 1

  Scenario 1 depicts a redirect use-case:

  When the quota is depleted, the subscriber is redirected to a web portal. When the credit is refilled, the OCS server notifies the BNG and provides a new quota. The configured out-of-credit-action when receiving a Final Unit Indication with action different from terminate is installed. See Figure: Online Charging scenario 1 - redirect (1/2) and Figure: Online Charging scenario 1 - redirect (2/2).

  Figure: Online Charging scenario 1 - redirect (1/2)

  
  Figure: Online Charging scenario 1 - redirect (2/2)

  

• scenario 2

  Scenario 2 depicts a terminate use case:

  When the quota is depleted after reception of a Final Unit Indication with action set to Terminate, the subscriber host is disconnected. The configured out-of-credit-action is ignored in this case. See Figure: Online Charging scenario 2 – terminate.

  Figure: Online Charging scenario 2 – terminate

  

Abbreviations used in the previous drawings: