| In recent years, with the rapid development of Internet, and especially the strong impulse of the relevant technology such as IPv6, Next Generation Network and the 3rd Generation Mobile Communication, it makes that the present network has manifested characteristics, which has numerous business and kinds of equipment, and is difficult to manage uniformly. Traditional network management based on SNMP(Simple Network Management Protocol)has exposed obvious weaknesses. It regards equipment as the centre, manages statically, and requires network administrators to know well the interface and names of various kinds of equipment, which is difficult to reach the objectives of flexibility and efficiency.Policy is a set of rules to manage, configure and control the access to network resources. Policy Based Network Management (PBNM) is used to simplify network management. PBNM describes and implements the high-level policy to manage the entire network rather than individual equipment. It translates policy into configuration commands and implements these configurations through the network in order that users can manage and configure network equipment with the simple commands. PBNM can provide automatic configuration of network equipment, and ensure end-to-end network management, as well as predicating and controlling preferential treatment. Network Management can be simplified while the network is regarded as an entity rather than a collection of individual network equipment.PBNM is consists of five main components including PMT(Policy Management Tool),PR(Policy Repository),PDP(Policy Decision Point),PEP(Policy Enforcement Point)and COPS(Common Open Policy Service). PMT is responsible for functions such as the policy editor, the policy representation, the rule translation, the policy validation, and the consistent check. And it store the edited policy into PR. PDP is responsible for retrieving the policy according with the condition from PR, and returning the decision-making and interpretative results to PEP. Then PEP performs the final policy.Though IP(IPv4) provides a best effort service, it doesn't ensure the QoS(Quality of Services)such as throughput and transmission delay. Now, there are many kinds of QoS ensuring technologies, including the Intserv(Integrated Services)model and Diffserv(Differentiated Services)model. The basic idea of Intserv is, for each data stream needing QoS treatment, to realize resource reservation on every router passed it by a certain signaled mechanism, and can realize end-to-end QoS business. The basic idea of Diffserv is to implement the complex functions of classification and schedule at network edge node, and for Aggregate Flow to apply PHB(Per-Hop Behaviors)according to the value of DS field marked properly in the headers of IPv4 or IPv6 packets. So, the complex process to every packet is pushed to network edge node. The primary task of the kernel network is only to apply corresponding forwarding behavior according to the code point of the header of the packet. In the Diffserv model, it doesn't need that the network middle nodes manage the states of work flows, so it has well expansibility.Taking two representative QoS policies as example, the paper combines PBNM and QoS, discusses the basic principle of policy information model and the mapping to the directory server, and extends it. It takes Netscape Directory Server as policy repository, designs and realizes the representation and storage scheme of QoS policy. Furthermore, it tests and analyses the performance of the directory server and relational database, and draws the conclusion that the directory server is more suit for policy repository.PIM(Policy Information Model)is an object-oriented information model to represent the policy information, which expands the CIM(Common Information Model)brought up by the DMTF(Distributed Management Task Force). The purpose is to build the basic element of policy and organize these elements effectively. Using these elements, you can build policy rapidly...
|
PDF Full Text Request