Application Detection and Control Rules
This section is intended for providing background on the different type of rules that can be used according to 3GPP specifications. Application Detection and Control (ADC) rules are used by the PCRF to control the behavior of the TDF or the PCEF enhanced with TDF. The ADC rules contains an application identifier for which the rule applies. The ADC rule can additionally contain enforcement information such as maximum bit rate (MBR). The ADC rules only contain the identity of the application being identified but leave unspecified in the standards what the application being identified is. The implication is that an application ID is an identifier that the TDF assigns to a specific application being identified, with a common interpretation between the TDF and the PCRF (there is no standardization defined for the application ID values). The specifications (such as 3GPP TS 23.203) indicate that one value of the application ID might represent one of the following attributes:
A group or category of applications
A list of URLs
A list of URIs
The main difference between a PCC rule and an ADC rule is that the ADC rule is not related to a bearer. This means that the ADC rule can be applied a MBR irrespective of APN-AMBR applied for the session. Additionally, in the uplink, the ADC rule is triggered irrespective of the bearer used by the UE for uplink traffic. Note also that , differently than PCC rules, ADC rules generate event triggers when a traffic flow matches the application ID specified in an ADC rule (Application-Start and Application-Stop), and together with the event trigger, the Application-instance-identified is also provided (how many occurrences of the same application ID the TDF has identified for that subscriber. As explained in the following sections, one additional type of rules supported by the SDG, specifically PCC rules enhanced with Application Detection or ePCC (PCC rules carrying the ADC-rules specific AVPs which are used to perform dynamic control of applications) is described.
PCEF Enhanced with TDF functionality
The PCEF (which is in PGW) can be enhanced for application detection. During the IP Connectivity Access Network (IP CAN) session establishment (and later during IP CAN session modification), the PCRF can download ADC rules to be used for application detection and policy control. This is in addition to the PCC rules which are downloaded for Policy and Charging Control (PCC) and bearer binding based on the service data flow (SDF) filters. Bearer binding refers to the association between a bearer and the PCC rules.
Types of Policy Rules on the TDF
According to 3GPP specifications, the following are the three types of policy rules:
PCC (Policy and Charging Control) rules (defined in 3GPP Release 7 specification onward), that can be either of the following:
Preconfigured (activated only by name by the PCRF or locally configured (with no PCRF interaction) rules). In such a case, preconfigured PCC rules can contain (within their internal definition that is never passed between PCRF and TDF/PCEF) criteria for detecting (and controlling) Layer 7 flows (applications)
Dynamic (fully dynamically provisioned by PCRF). In such a case, they do not contain any Layer 7 information, and can therefore be only used for managing flows at Layer 4 (4-tuples)
ADC rules (Application Detection and Control rules defined in 3GPP Release 11 specification) can be either of the following:
Preconfigured (activated only by name by the PCRF or locally configured (with no PCRF interaction) rules)
Dynamic (fully dynamically provisioned by PCRF). In a TDF network, preconfigured PCC rules and preconfigured or dynamic ADC rules can be used to detect, perform control actions, and charge flows at Layer 7. Dynamic PCC rules can only be used to control flows at Layer 4 (and because it is a TDF, with no control actions on bearers).
Enhanced PCC rules (non-standard definition of PCC rules, which contain all the standard definition of a PCC rule and the application detection parameters of an ADC rule that are not contained in a PCC rule) are supported. Enhanced PCC rules (ePCC rules) are exclusively dynamic.
Currently, Services Control Gateway supports PCC and ePCC rules.