RFC 4006, Diameter Credit Control Application, specifies a graceful service termination mechanism using the Final-Unit-Indication to indicate that an Answer message contains the final units for the service. When the final units are consumed, the action is specified with the Final-Unit-Action AVP.
Final-Unit-Indication ::= < AVP Header: 430 >
{ Final-Unit-Action }
*[ Restriction-Filter-Rule ]
*[ Filter-Id ]
[ Redirect-Server ]
In SR OS, with the Final-Unit-Action AVP = TERMINATE, the subscriber host or session is disconnected. With the Final-Unit-Action = REDIRECT or RESTRICT_ACCESS, the out-of-credit-action as specified in the credit-control-policy or category-map is executed. In the case of REDIRECT, the URL specified in the Redirect-Server AVP is used when IPv4 HTTP redirect is enabled as the out of credit action and the following conditions are met:
a Final-Unit-Indication AVP is present in the Multiple-Services-Credit-Control AVP of a CCA message
the Final-Unit-Action AVP is set to REDIRECT (1)
a Redirect-Server AVP is included with the following:
the Redirect-Address-Type AVP set to URL (2)
the Redirect-Server-Address AVP containing the URL to use for this rating group (category-map)
the out of credit action for the corresponding rating group is set to change-service-level using one of the following CLI commands:
configure subscriber-mgmt credit-control-policy policy-name out-of-credit-action change-service-level
configure subscriber-mgmt category-map category-map-name category category-name out-of-credit-action-override change-service-level
an IPv4 HTTP redirection action with allow-override is specified in the exhausted credit service level context for the corresponding rating group using the command configure subscriber-mgmt category-map category-map-name category category-name exhausted-credit-service-level ingress-ip-filter-entries entry entry-id action http-redirect url allow-override.
In all other cases, the URL specified in the Redirect-Server-Address AVP is ignored and the configured URL is used if HTTP redirect is enabled as the out of credit action.
The Restriction-Filter-Rule and Filter-Id AVPs included in the Final-Unit-Indication AVP are ignored.
Use the following show commands to find the active URL when an out-of-credit-action change-service-level is triggered that includes an IPv4 HTTP redirect action in the credit control ingress IP filter entries:
show service active-subscribers filter [subscriber sub-ident-string]
This command displays the active IPv4 ingress filter identifier.
show filter ip ip-filter-id
With the filter identifier found in the previous command, this command displays the credit control inserted entries (Origin = ‟Inserted on ingress by Credit Control”), including the IPv4 HTTP redirect action with the static configured URL. The optional allow-radius-override flag may be shown. This flag is common for RADIUS and Diameter-based overrides, where the flag indicates that the URL may have been overridden by the Diameter Credit Control server. Use the next command to determine if an override was specified.
show service active-subscribers credit-control
This command displays the URL received from the Diameter Credit Control server for a rating group or category with ‟Out of Credit Action = ChangeServiceLevel” active. The URL is displayed in the ‟HTTP Rdr URL Override” field.