CCA (Credit-Control-Answer)

Message Function

The Credit Control Answer (CCA) command, indicated by the Command-Code field set to 272 and the 'R' bit cleared in the Command Flags field, is sent by the PCRF to the PCEF in response to the CCR command. It is used to provision PCC rules and event triggers for the session and to provide the selected bearer control mode for the IP-CAN session. If the PCRF performs the bearer binding, PCC rules will be provisioned at bearer level. The primary and secondary CCF and/or primary and secondary OCS addresses may be included in the initial provisioning.

here are three types of CCA message: CCA-Initial, CCA-Update and CCA-Terminate.

CCA-Initial: After processing the IP-CAN session authorization establishment request message, the PCRF generates a policy and sends it to the PCEF through an IP-CAN session authorization answer message.
CCA-Update: After processing the IP-CAN session authorization update request message, the PCRF generates a policy and sends it to the PCEF through an IP-CAN session authorization answer message.
CCA-Terminate: After processing an IP-CAN session authorization request message, the PCRF generates a policy and sends it to the PCEF through an IP-CAN session termination authorization answer message.

CCA-Initial Message Format

<CC-Answer> ::=  < Diameter Header: 272, PXY >              
                 < Session-Id >                             
                 { Auth-Application-Id }                    
                 { Origin-Host }                            
                 { Origin-Realm }                           
                 [ Result-Code ] [ Note 1]                  
                 [ Experimental-Result ]                    
                          { Vendor-Id }                     
                          { Experimental-Result-Code }      
                 { CC-Request-Type }             
                 { CC-Request-Number }                      
                *[ Event-Trigger ] [ Note 2]                
                *[ Charging-Rule-Install ] [ Note 3]        
                          *[ Charging-Rule-Definition ]          
                                    { Charging-Rule-Name }             
                                    [ QoS-Information ]    
                                            [ Max-Requested-Bandwidth-UL ]   
                                            [ Max-Requested-Bandwidth-DL ]   
                                            [ Guaranteed-Bitrate-UL ]        
                                            [ Guaranteed-Bitrate-DL ]        
                                            *[ AVP ]                           
                                   [ Monitoring-Key ]                 
                                   [ X-HW-Service-Type ]     
                                   [ X-HW-ACL-Group-Name ]   
                                   [ X-HW-Interim-Interval ] 
                                   *[AVP]                             
                          *[ Charging-Rule-Name ]                
                          *[ AVP ]                                 
                *[ QoS-Information ] [ Note 4]              
                          [ Max-Requested-Bandwidth-UL ]         
                          [ Max-Requested-Bandwidth-DL ]         
                          [ Guaranteed-Bitrate-UL ]              
                          [ Guaranteed-Bitrate-DL ]              
                          *[ AVP ]                                 
                *[ Usage-Monitoring-Information ] [ Note 5] 
                          [ Monitoring-Key ]                    
                          [ Granted-Service-Unit ]              
                                   [ CC-Time ]                        
                                   [ CC-Total-Octets ]                
                          *[ AVP ]                                
                 *[ AVP ]

The NetEngine 8000 F receives but does not process *[AVP]. That is, the NetEngine 8000 F processes only the AVPs listed in this document and ignores other optional AVPs.

Note Index	Note Description
[Note1]	Either the Result-Code AVP or Experimental-Result AVP must exist.
[Note2]	This AVP indicates a group AVP for policy deletion. In case of a dynamic policy, the Charging-Rule-Name AVP indicates the PCC rule name generated by the PCRF. Otherwise, the AVP indicates the predefined rule name.
[Note3]	This AVP indicates the installation policy and consists of the Charging-Rule-Definition and Charging-Rule-Name AVPs. The Charging-Rule-Definition AVP refers to the PCC rule generated on the PCRF and is usually called a dynamic policy. This AVP also consists of several AVPs. The Charging-Rule-Name AVP refers to the policy configured on the PCEF. On the PCEF, only the rule name (template name) must be provided to instruct the PCEF to apply a rule to a service flow, providing the definition of the rule is not required. A policy is activated or deactivated depending on the predefined rule and is generally called a static policy.
[Note4]	The QoS-Information AVP at the command level includes user bandwidth information. The QoS-Information AVP at the service level refers to the QoS-Information AVP in the Charging-Rule-Definition AVP.
[Note5]	The Usage-Monitoring-Information AVP in CCA-Initial message indicates the usage allocated by the PCRF.
[Note6]	When the Event-Trigger AVP is sent by the PCRF to the PCEF, the Event-Trigger AVP indicates an event in which the PCC rule is requested again.

CCA-Update Message Format

<CC-Answer> ::=  < Diameter Header: 272, PXY >                       
                 < Session-Id >                                      
                 { Auth-Application-Id }                             
                 { Origin-Host }                                     
                 { Origin-Realm }                                    
                 [ Result-Code ] [ Note 1]                           
                 [ Experimental-Result ]                             
                         { Vendor-Id }                               
                         { Experimental-Result-Code }                
                 { CC-Request-Type }                              
                 { CC-Request-Number }                            
                 *[ Supported-Features ]
                 *[ Event-Trigger ] [ Note 2]                      
                 *[ Charging-Rule-Remove ] [ Note 3]               
                         *[ Charging-Rule-Name ]                     
                         *[ AVP ]                                    
                 *[ Charging-Rule-Install ] [ Note 4]              
                         *[ Charging-Rule-Definition ]        
                                 { Charging-Rule-Name }              
                                 [ QoS-Information ]                 
                                       [ Max-Requested-Bandwidth-UL ]
                                       [ Max-Requested-Bandwidth-DL ]
                                       [ Guaranteed-Bitrate-UL ]     
                                       [ Guaranteed-Bitrate-DL ]     
                                      *[ AVP ]                       
                                 [ Monitoring-Key ]                  
                                 [ X-HW-Service-Type ] [ Note 5]              
                                 [ X-HW-ACL-Group-Name ] [ Note 6]            
                                 [ X-HW-Interim-Interval ] [ Note 7]          
                                *[ AVP ]                             
                         *[ Charging-Rule-Name ]                     
                         *[ AVP ]                                    
                 *[ QoS-Information ] [ Note 8]                     
                          [ Max-Requested-Bandwidth-UL ]             
                          [ Max-Requested-Bandwidth-DL ]             
                          [ Guaranteed-Bitrate-UL ]                  
                          [ Guaranteed-Bitrate-DL ]                  
                         *[ AVP ]                                    
                  *[ Usage-Monitoring-Information ] [ Note 9]       
                          [ Monitoring-Key ]                         
                          [ Usage-Monitoring-Level ]                 
                          [ Granted-Service-Unit ]                   
                                 [ CC-Time ]                         
                                 [ CC-Total-Octets ]                 
                         *[ AVP ]                                    
                  *[ AVP ]

The NetEngine 8000 F receives but does not process *[AVP]. That is, the NetEngine 8000 F processes only the AVPs listed in this document and ignores other optional AVPs.

Note Index	Note
[Note1]	The Result-Code AVP is an error code. Either the Result-Code or Experimental-Result AVP must exist.
[Note2]	When the Event-Trigger AVP is sent by the PCRF to the PCEF, the Event-Trigger AVP indicates an event in which the PCC rule is requested again.
[Note3]	The Charging-Rule-Remove AVP indicates a removal policy and consists of several AVPs. If the policy is a dynamic policy, the Charging-Rule-Name AVP is the PCC rule name generated by the PCRF. Otherwise, the Charging-Rule-Name AVP is the predefined rule name.
[Note4]	The Charging-Rule-Install AVP indicates the installation policy and consists of the Charging-Rule-Definition and Charging-Rule-NameAVPs. The Charging-Rule-Definition AVP refers to the PCC rule generated on the PCRF and is usually called a dynamic policy. This AVP also consists of several AVPs. The Charging-Rule-Name AVP refers to the policy configured on the PCEF. On the PCRF, only the rule name (template name) must be provided to instruct the PCEF to apply a rule to a service flow; providing the definition of the rule is not required. A policy is activated or deactivated depending on the predefined rule and is generally called a static policy.
[Note4]	The QoS-Information AVP at the command level includes user bandwidth information. The QoS-Information AVP at the service level refers to the QoS-Information AVP in the Charging-Rule-Definition AVP.
[Note5]	The X-HW-Service-Type is a private AVP.
[Note6]	The X-HW-ACL-Group-Name is a private AVP.
[Note7]	The X-HW-Interim-Interval is a private AVP.
[Note8]	The QoS-Information AVP at the command level includes user bandwidth information. The QoS-Information AVP at the service or rule level refers to the QoS-Information AVP in the Charging-Rule-Definition AVP.
[Note9]	The Usage-Monitoring-Information AVP in a CCA-Update message indicates the amount used by the user.

CCA-Terminate Message Format

<CC-Answer> ::=  < Diameter Header: 272, PXY >   
                   < Session-Id >                
                   { Auth-Application-Id }       
                   { Origin-Host }               
                   { Origin-Realm }              
                   [ Result-Code ] [Note1]       
                   [ Experimental-Result ]       
                        { Vendor-Id }               
                        { Experimental-Result-Code }
                   { CC-Request-Type}          
                   { CC-Request-Number}          
                   *[ AVP ]

The NetEngine 8000 F receives but does not process *[AVP]. That is, the NetEngine 8000 F processes only the AVPs listed in this document and ignores other optional AVPs.

Note Index	Note Description
[Note1]	Both the Result-Code AVP and the Experimental-Result-Code AVP define an error code. In an IP-CAN session termination authorization answer message, either the Result-Code or Experimental-Result-Code AVP must exist.

Reference Standards

3GPP TS 29.212 V9.7.0 clause 5.6.3