An Overview of Policy-based Management

Policy-based management involves the following:

• Developing a set of policies (rules) that describe the desired network configuration.

• Baselining your current network. The baseline data is used to confirm that the network is capable of handling a particular policy, and for other tasks such as long-term planning.

• Using tools that translate policies into individual device-configuration changes. These configuration changes can then be applied to the affected devices.

• Reporting on whether the policy is being met. Whether the policy was not implemented correctly or a subsequent change undoes a previously implemented policy, you need a method to validate that things work as you expected. This validation is achieved with service level agreements (SLAs).

Although the practice of defining computing policies has been around for decades, the idea is relatively new with distributed networks. Not until recently have networking technologies become sophisticated enough to implement, enforce, and report on policy-related functionality.

Voice and video over packet networks have driven the need for QoS, which in turn has driven the need for policy-based management tools. QoS can be difficult to implement and maintain across large numbers of switches and routers. Policy-based management tools can simplify the consistent implementation and management of QoS-related features.

NOTE

Policy-based management does not necessarily simplify the task of network-wide device configuration and validation. The configuration changes that policy software make to network devices can be quite complex and possibly destructive to the normal operation of the network. Before using policy-based configuration tools, you should learn the underlying technologies the tool configures on the devices.

At the time of this writing, few policy-based tools have been released, partly due to the complexity of developing such tools and partly due to their potentially destructive nature to networks.