Understanding Predefined Policy and Charging Control Rules
On Service Control Gateway, you can configure policy and charging control (PCC) rules to define the treatment to be applied to specific service data flows or to packets associated with specific applications. These predefined PCC rules contain a from clause that identifies the service data flows or applications, and a then clause that specifies the PCC action profile that identifies the treatment to apply.
A Service Control Gateway predefined PCC rule can be used in three ways:
When PCC rules are under static control, predefined rules are the only rules used. The provisioning of PCC rules involves no interaction from the policy and charging rules function (PCRF) or a RADIUS server.
When PCC rules are under dynamic control, a predefined PCC rule must be activated by the PCRF. (With dynamic control, PCC rules can also be sent from the PCRF.)
When PCC rules are under RADIUS server control, a predefined PCC rule must be activated by the RADIUS server.
This topic includes the following sections:
Understanding Service Data Flow Filters
Service data flow (SDF) filters (flow identifiers) are specified in the from clause of a PCC rule to identify IP packets belonging to a particular Layer 3 or Layer 4 service data flow. If the IP packet matches the SDF filter in a PCC rule, the treatment specified in the PCC action profile in the then clause of the rule is applied.
To configure Layer 3 or Layer 4 SDF filters, you specify one or more of the following parameters:
Source IP address
Destination IP address
Layer 4 protocol (UDP or TCP)
Understanding Application Filters
Applications or application groups are specified in the from clause of a PCC rule to identify IP packets belonging to a specific application. If the IP packet is for an application identified in a PCC rule, the treatment specified in the PCC action profile in the then clause of the rule is applied.
To configure application-aware PCC rules, you can specify one or more of the following parameters:
application—Specifies the name of an application. This can be a Layer 7 protocol (for example, HTTP) or a particular application running on a Layer 7 protocol, such as Facebook and Yahoo Messenger.
application-group—Specifies the name of an application group, which can be used to process a number of applications or subgroups at the same time.
Application-aware PCC rules that reference specified applications can include wildcard or specific Layer-3 SDF filters, Layer-4 SDF filters, or both.
Understanding PCC Action Profiles
A PCC rule configuration includes an action profile in the then clause that defines the treatment to apply to a service data flow or to a packet belonging to an application identified in the from clause of the rule. You can configure a PCC action profile that is used in one or more PCC rules to provide the following functionality:
HTTP redirection—Specifies HTTP redirection to a URL. You can use this action only for PCC rules that match only HTTP-based applications and all flows.
HTTP Steering path—Specifies an IPv4 or IPv6 address for steering HTTP packets. You can use this action only for PCC rules that match only HTTP-based applications and all flows.
A single PCC rule can support either HTTP redirection or HTTP steering path, but not both.
Steering with a routing instance—Specifies a routing instance for steering of packets to a third-party server to apply services or to a local or external service chain. You can configure different routing instances for traffic from the Service Control Gateway subscriber (uplink) and traffic to the subscriber (downlink).
Keep existing steering—Specifies that steering attributes configured in a PCC action profile that a PCC rule applies to a data flow session when it begins will continue to be applied to the data flow when the PCC rule match conditions are modified, deleted, or added to.
Forwarding class—Specifies the forwarding class that you want assigned to the packet.
Maximum bit rate—Specifies the maximum bit rate for uplink and for downlink traffic.
HCM profile—Specifies the profile that identifies the HTTP header enrichment rules to apply. You can use this action only for PCC rules that match only HTTP-based applications and all flows.
Gating status—Specifies whether to block or to forward IP packets.