RFC 3318 (rfc3318) - Page 3 of 70
Framework Policy Information Base
Alternative Format: Original Text Document
RFC 3318 Framework Policy Information Base March 2003 2. General PIB Concepts 2.1. Roles The policy to apply to an interface may depend on many factors, such as immutable characteristics of the interface (e.g., Ethernet or frame relay), the status of the interface (e.g., half or full duplex), or user configuration (e.g., branch office or headquarters interface). Rather than specifying policies explicitly for each interface of all devices in the network, policies are specified in terms of interface functionality. To describe these functionalities of an interface, we use the concept of "Roles". A Role is simply a string that is associated with an interface. A given interface may have any number of roles simultaneously. Provisioning classes have an attribute called a "RoleCombination" which is a lexicographically ordered set of roles. Instances of a given PRovisioning Class are applied to an interface if and only if the set of roles in the role combination matches the set of the roles of the interface. Thus, roles provide a way to bind policy to interfaces without having to explicitly identify interfaces in a consistent manner across all network devices. That is, roles provide a level of indirection to the application of a set of policies to specific interfaces. This separates the policy definition from device implementation specific interface identification. Furthermore, if the same policy is being applied to several interfaces, that policy needs to be pushed to the device only once, rather than once per interface, as long as the interfaces are configured with the same role combination. We point out that, in the event that the administrator needs to have a unique policy for each interface, the administrator can configure each interface with a unique role. The PEP sends all its Capability Set Names, Role Combinations, Policy Controlled Interfaces, and their relationships to the PDP in the first COPS request (REQ) message for a handle, and whenever any updates or deletes occur. The PDP can install new instances or change existing instances of these PRIs. This operation can also occur in subsequent request messages generated in response to COPS state synchronization (SSQ) requests and local configuration changes. The comparing of roles (or role combinations) is case sensitive. Sahita, et. al. Informational
