Section: 16a.2 Diameter Accounting
Content: Diameter Accounting shall be used according to RFC 7155 [120]. The Diameter accounting client function may reside in a GGSN/P-GW. The Diameter accounting client may send information to an accounting server, which is identified during the APN provisioning. The accounting server may store this information and use it to automatically identify the user. This information can be trusted because the PS access network has authenticated the subscriber (i.e. SIM card and possibly other authentication methods). Diameter Accounting messages may be used during both primary and secondary PDP context activation for non-EPC based packet domain (both the default bearer and dedicated bearer for the EPC based packet domain) and deactivation procedures respectively. If the AAA server is used for IPv4 address and/or IPv6 prefix assignment, then, upon reception of a Diameter Accounting-Request STOP message for all IP-CAN bearers associated to an IP-CAN session defined by APN and IMSI or MSISDN, the AAA server may make the associated IPv4 address and/or IPv6 prefix available for assignment. For PDN/PDP type IPv4v6 and deferred IPv4 address allocation, when the IPv4 address is allocated or re-allocated, the accounting session that was established for the IPv6 prefix allocation shall be used to inform the accounting server about the allocated IPv4 address by sending Diameter Accounting-Request Interim-Update with Framed-IP-Address AVP and its value field containing the allocated IPv4 address. Similarly, the release of IPv4 address shall be indicated to the accounting server by sending Diameter Accounting-Request Interim-Update without the Framed-IP-Address AVP.