A policy rule is an If-Then statement that has a set of conditions and actions. If the conditions are met, the actions are performed. You create policy rules within the CMP system, using a policy wizard that organizes a large number of conditions and actions to assist you in the construction of policy rules. After you create policy rules, you manually deploy the rules to MPE devices.
You can combine policy rules to provide additional power and flexibility. When there are multiple policy rules, the order in which the policy rules are evaluated can also influence MPE device activity, so the order of evaluation is also configurable through the CMP system. You can also organize policy rules into groups to simplify the management of policy rules. You can cause groups of rules to be executed.
The following are sample scenarios for which you might use policy rules:
- You can modify the contents of protocol messages using policy rules. For example, you could use a policy rule to override the requested bandwidth parameters in a request.
- You can create policy rules that track the use of resources for devices in the network and implement limits on how those resources are used. For example, some cable modems have limits on the number of dynamic flows that they can support. Using policy rules, you can ensure that a cable modem does not exceed this limit.
- Some protocols allow for the provisioning of default Quality of Service (QoS) parameters for subscribers. With these protocols, policy rules can implement subscriber tiers where different subscribers have different bandwidth available.
- You can configure policy rules to monitor the reservation of bandwidth on network elements and notify operators when an element exceeds certain threshold levels.
- In many protocols, the policy server acts as an intermediary between the Application Managers and the QoS enforcement devices. Many of these QoS enforcement devices implement proprietary features that are activated through the use of standard (or non-standard) fields in protocol messages. Using policy rules, you can activate these proprietary features on behalf of the Application Managers, thus allowing them to use these features without modification.