The Research And Design Of PDP In Policy-Based QoS Network Management System

Policy-Based Network Management ( PBNM ) which is put forward for QoS and security management becomes the focus of the network management now. PBNM has already reflected user's requests for network applications, and also embodied the management objectives that the network manger makes. It showed that can reflect the models of the Pyramid of above-mentioned characteristics. The policymakers describe policies with the abstract policy language, according to the demands of user and the goals of administrator. Starting from the administration and supervision authorities level, the model is divided into two parts: the system management facing network applications and the network management facing that the policies carry out. From the view of user, network applications are realized through the policies mechanism finally; but from the view of network mangers, the management objectives are carried out by the corresponding network entity through the policies mechanism finally.The policies are a set of business rules guiding and determining how to manage, assign and controll network resources. The manger can describe network functions with the abstract policy language from a whole network, not stickle it in the concrete network equipments and technological details. Through the operation of PBNM, the high-level policies are distributed automatically to the concrete equipments of the whole network. The paper carries on deep researches to PBNM and proposes a design and implementation of a concrete PBNM which realizes end-to-end QoS.At first we introduce the work which IETF RAP WG and Policy Framework WG make from PBNM systemly and overally, especially carry on key research to the PBNM in the fields of QoS.In order to set up a practical system, IETF not only cooperated with DMTF to have defined PCIM (Policy Core Information Model) and expansion, but also proposed the PBNM realization frame. On the basis of CIM (Common Information Model), IETF has defined policy rules by the condition-action form. The rule carries out its action after triggering the condition. Network system under the policy control is a piece of state machine, policies determine equipment's legal state. The general form of rule is" IF Condition THEN Action ".IETF divided the PBNM architecture into four major function entities which are PolicyRepository, PMT (Policy Mangement Tool), PDP (Policy Decision Point) and PEP(Policy Enforcement Point). User can use PMT to editor the policies; The PMT stores the policies into PolicyRepository after dealing with the policies; PDP is responsible for the explanation with policy rules and initiate to carry out; PEP carries out the actions of policy rules actually, and feedbacks the result of carrying out. In addition, IETF has also made communication protocol COPS (Common Open Policy Service) which exchanges the policy informations, COPS-RSVP and COPS-PR expand respectively the communication protocol (COPS). Besides, IETF has expanded the policy core information model in the fields of QoS and network security. In QoS, it has already made QPIM (Policy QoS Information Model). After IETF issues about PBNM standards, most research work, including some products, regard it as the criterion, and bring into the track which is the condition-action policy rules model and PDP, PEP function dividing, This is favorable to standardization.The advantage of DiffServ is the expansibility when the quantity of the flow increases, and the core part in the extensive network can give play to this advantage effectively most. However, it assures the aggregate flow to be guaranteed QoS to DS behavior, does not have any assurance to the actions of each microflow. In this one, IntServ can appointed QoS of each flow, and it is an ideal QoS to user. Oppositely, interior gateways want to hold each flow's state, so expansion is a difficult point. For giving play to above-mentioned the two each advantages to the maximum extent, it proposes end-to-end using IntServ service, and the core backbone network part using the structure of DiffSer...