The Architecture Of Policy-based QoS Control System In Mobile Environment

Mobile communication mainly offers multi-media services in the future,system have to provide multi-media services such as data, audio, video with highspeed and QoS guarantee. And also can adapt changes. The system for now willhave trouble in meeting the demand of future communication: wireless resourceshortage, unstable wireless communication channel, and turnovers happened incommunication. So when host change position from one location to other one, theincoming location has to reserve enough resource avoiding communicationinterruption. Therefore whether the mobile host can reserve resource beforearrivingdestinationiscrucialforQoSguarantee.Policyisasetofrulestomanage,configureandcontroltheaccesstonetworkresources. Policy Based Network Management (PBNM) is used to simplifynetwork management. PBNM describes and implements the high-level policy tomanage the entire network rather than individual equipment. It translates policyinto configuration commands and implements these configurations through thenetwork in order that users can manage and configure network equipment with thesimple commands. PBNM can provide automatic configuration of networkequipment, and ensure end-to-end network management, as well as predicatingand controlling preferential treatment. Network Management can be simplifiedwhile the network is regarded as an entity rather than a collection of individualnetworkequipment.Inordertosetupapracticalsystem,IETFnotonlycooperatedwithDMTFtohave defined PCIM (Policy Core Information Model) and expansion, but alsoproposedthePBNMrealizationframe.OnthebasisofCIM(CommonInformationModel), IETF has Abstract-V -defined policy rules by the condition-action form.Therule carries out its actionaftertriggeringthe condition.Network system underthepolicycontrol is a pieceofstatemachine; policies determine equipment's legalstate.Thegeneralformofruleis"IFConditionTHENAction".PBNM is consists of five main components including PMT(Policy ManagementTool),PR(PolicyRepository),PDP(PolicyDecisionPoint),PEP(PolicyEnforcementPoint)andCOPS(CommonOpenPolicyService).PMTisresponsible for functions such as the policy editor, the policy representation, therule translation, the policy validation, and the consistent check. And it store theedited policy into PR. PDP is responsible for retrieving the policy according withtheconditionfromPR,andreturningthedecision-makingandinterpretativeresultstoPEP.ThenPEPperformsthefinalpolicy.Because of changeable wireless channel, packet loss rate, mobile hostsfrequently position change. Mobile environment can have strong influence onbusiness's QoS. These factors above will finally have negative influence on theserviceofferedbyInternet.Andcallforhigherqualityofdatastream.Policybasednetwork management have a advantage that it can make network managementsystem adapt the changeable. by the help of policy based management, networkcan be more efficient in the wireless environment. And network can provide morestable QoS. Local policy server, central policyserver, PolicyEnforcement Point isthree important entity. Recovering, rebuilding the influence path and reducinginterruption during the changing time are the most important factors for the goodQoSprovidedbynetworktomobilehost.For realizingend-to-end QoS withpolicythought,this paper designs our ownnetwork management system based on PBNM of what IETF puts forward. ThemodeisaconcentratingtypeframeofClients/Server.This paper discusses the inner structure, function and the connection. First ofall, it plays a role in forming a connecting link in an intact PBNM; it interpretshigh-level policies defined at upper PMT into CLIs that finally resolve it to theconcrete equipment, accordingly finishes the automatic arrangement based onpolicyrules.Secondly,thedeploymentofpolicyis adjusteddynamicallyaccordingto the dynamic change of network states. At last, it can offer the function situationin charge of the network to the administrator; help him carry on the definition ofthe high-level policy. During the management of the whole network, it can alsocarry on the service level negotiation with other policy servers, and finish end-to-endQoS.The policy server and mobile host reserve resource by using"two-level"negotiation mechanism."The first level"means the mobile host communicateswith local policy server directly."The second level"means local policy servercommunicates with overall policy server. The communication control layer andtransport layer can be divided by using negotiation mechanism which also offersstable QoS in the wireless environment condition. Policy server can use differentmethod to make decision timely that will persist with mobile host's positionchanges. Thus .The decision made by policy server will be faster and moreaccuratelyandTheQoSofmobilehostwillbeguaranteed.We can develop mobile IP protocol and make it right for"two-level"communication mechanism; however, we choose COPS protocol and makeextension of COPS protocol. And add new extensible message. The advantage isthat when mobile management is independent with QoS negotiating protocol andusing mobile triggered message instead, there will less QoS service interruption,and also can avoid reserving source in the same path again. The whole process isgoing to be more simply, flexible that can persist with numbers of policy client,and easier to define more objects. So it will competent with this unique negotiatedmechanics.At present, there is standard of PCIM in Mobile IP, so policy is defineddirectly .Because of the limit of time and condition, the papers don't test theprocess that guarantees end-to-end QoS. The mobile host's negotiated protocol isthenewlyextendedprotocol;itsinnovationprovidescertainreferencevalueforthestudy of policy-based resource reserved management in policy managementnetwork. The resolve of newly defined COPS protocol solves the communicationquestion between PEPand PDP, which provides good base for the further studyofresourcereservedmanagementinmobileenvironmentpolicybasednetwork.