PCRF vs PCEF
PCRF (Policy and Charging Rules Function) and PCEF (Policy and Charging Enforcement Function) are both closely related functional entities, which include policy control decision making and flow based charging control functionalities. PCRF is designed to provide network control relating to the service data flow detection, QoS, and flow based charging controlling to the PCEF, whereas PCEF basically provides user traffic handling and QoS at the Gateway. Moreover, it is also responsible for providing service data flow detection, counting along with online and offline charging interactions.
What is PCRF?
PCRF (Policy and Charging Rules Function) is a dedicated policy functional entity that is standardized in 3GPP and provides necessary policy functions for bandwidth and charging on multimedia networks. This was introduced in September 2007 along with the standards for the 3GPP Policy Charging Control (PCC) architecture. PCRF function acts as a part of the PCC architecture, which also consists of the Policy and Charging Enforcement Function (PCEF) and the Proxy Call Session Control Function (P-CSCF).
Generally, PCRF aggregates information inside the hosting network; therefore, it can be considered as a part of the entire network architecture. PCRF makes intelligent policy decisions for each subscriber active in the network automatically. Almost all operational support systems (OSS) along with other sources (such as portals) in real time support the creation of rules which ultimately help policy making. This is a clear sign of a network that offer multiple services, charging rules, and quality of service (QoS) levels.
Basically, PCRF operates according to the received session and media related information through the Application Function (AF). Then this information is transferred to the AF of traffic planning events. The PCRF is the entity which applies PCC rules to the PCEF using the Gateway interface. Most of the subscriber information databases and other specialized functions are accessible to PCRF. Apart from that, information related to charging systems are also accessible to PCRF in a more scalable and centralized manner. Owing to the real time operation of PCRF, it generates an increased strategic significance and broader potential role than many other legacy policy engines.
What is PCEF?
The Policy and Charging Enforcement Function or commonly known as PCEF is the functional entity which includes policy enforcement along with follow based charging functionalities. This functional element is located at the Gateway and it is responsible of providing controller functions in traffic handling and QOS at the Gateway over the user plane, and providing service data flow detection, counting with including online and offline different charging interactions.
Generally, PCEF may select an appropriate PCC (Policy and Charging Control) rule for the evaluation process of each received packet against the service data flow filters of PCC rules. This will be mainly done by considering the order of precedence for each PCC rule. Once a packet is matched with a service data flow filter, it is considered as the packet matching process of that particular packet is completed. Therefore, the PCC rule for that filter can be applied without a problem.
When considering a certain service data flow, which is controlled by the policy control, PCEF plays a major role. The service data flow is allowed to pass through the gateway by the PCEF, only when the corresponding gate is accessible.
What is the difference between PCRF and PCEF?
• Both PCEF and PCRF are functional entities involved in different levels of charging policing implementation.
• Both PCEF and PCRF use Policy and Charging Control rules.
• The PCRF includes mainly policy control decision and flow based charging control functions whereas, the PCEF is more concerned of policy enforcement and follow based charging functions.
• When considering predefined PCC rules, they are preconfigured by the PCEF, but the Activation or the Deactivation of these predefined PCC rules can only be done by PCRF.
• PCEF supports online and offline charging interactions whereas PCRF does not.