ding to IP application type, IP address, protocol type, and other variables. It allocates unused bandwidth more effectively than other QoS mechanisms do, and it uses priority tables to give critical applications the most immediate access to unused bandwidth. Policy-Based Management, COPS, and LDAP A few additional concepts are relevant to QoS: policy-based management, COPS, and LDAP. Policy-Based Management The idea behind policy-based networking is to asso- ciate information about individual users, groups, organizational units, entire orga- nizations, and even events (such as the beginning of the accounting department's month-end closing) with various network services, or classes of service. So on a very granular basis, and on a time-sensitive basis, you can ensure that each user is receiving the QoS needed for the particular application at a specific time and place. COPS COPS is an IETF query-response-based client/server protocol for support- ing policy control over QoS signaling protocols, such as RSVP. It is part of the Internet Protocol suite, as defined by IETF RFC 2748. COPS addresses how servers and clients on a network exchange policy information, and it transmits informa- tion between a policy server and its clients, which are policy-aware devices such as switches. COPS is composed of policy decision points (PDPs), which are servers on which policies are stored, and policy enforcement points (PEPs), the clients on which the policies are enforced. There are two COPS models: Provisioning Model-In the Provisioning Model, the PEP reports its decision-making capabilities to the PDP, which then downloads the pertinent policies onto the PEP. The PEP uses these policies to make its own decisions. In this model, the policy information base is the repository of the policies. The Next-Generation Network Infrastructure Outsourcing Model-With the Outsourcing Model, the simplest mode, all policies are stored at the PDP. When a PEP needs to make a decision, it sends the relevant information to the PDP, which then anal