• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.7B
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• pp.697-710
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• 2004

Differentiated services (DiffServ) model has been prevailed as a scalable approach to provide quality of service in the Internet. However, there are difficulties in providing the guaranteed service in terms of end-to-end systems since differentiated services network considers quality of service of aggregated traffic due to the scalability and many researches have been mainly focused on per hop behavior or a single domain behavior. Furthermore quality of service may be time varying according to the network conditions. In this paper, we study dynamic class mapping mechanism to guarantee the end-to-end quality of service for multimedia traffics with the minimum network cost over differentiated services network. The proposed algorithm consists of an effective implementation of relative differentiated service model, quality of service advertising mechanism and dynamic class mapping mechanism. Finally, the experimental results are provided to show the performance of the proposed algorithm.

• Journal of the Korea Society of Computer and Information
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• v.9 no.2
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• pp.139-147
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• 2004

To provide Internet QoS, the IETF Proposed two models of Integrated Services (IntServ) and Differentiated Services (DiffServ) Unlike IntServ where resource reservation and admission control is Per-flow based using RSVP. DiffServ supports aggregated traffic classes to provide various QoS to different classes of traffics. However a dynamic QoS management system is required to dynamically provide differentiated QoS for customers who require dynamic QoS change. This paper designed and implemented therefore a policy-based QoS management system to manage effectively and configure dynamically QoS of DiffServ networks. The validity of the system has been verified by the experimentation on the Linux-based DiffServ network.

• Proceedings of the Korea Information Assurance Society Conference
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• 2004.05a
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• pp.43-50
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• 2004

Diffserv Network DSCP(Differentiated Service Code Point)는 8bit로 구성되어 있고, 그 중 6bit만 사용되고, 나머지 2bit는 비워져 있는 상태로 있다. 이 2bit를 사용하여, DF(Default Forwarding), EF(Expedited Forwarding), AF(Assured Forwarding)의 DSCP 에 각각의 Service Class Code Point를 부여해서 사용자의 패킷을 구분하여 서비스하는 DiffServ 같은 경우 상용화가 되었을 때, DiffServ를 서비스하는 망에서 동일한 DiffServ 정책을 설정해서 사용할 수 있는 기법을 제안한다.

• Proceedings of the Korean Information Science Society Conference
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• 2004.04a
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• pp.721-723
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• 2004

오늘날의 인터넷은 QoS를 보장하기 위해 다양한 방법을 사용하고 있는데, 본 논문에서는 Integrated-QoS 개념을 제안하고 이를 기반으로 Admission Control을 실행하는 Enhanced Differentiated Service(DiffServ)를 설계하였다. 본 논문은 IntServ(Integrated Service)와 DiffServ(Differentiated Service)의 장점을 결합하여, EF 클래스에 속하는 다수의 흐름들(flows)에 기존보다 QoS가 더욱 보장된 서비스를 제공할 수 있는 방안을 제시한다.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10e
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• pp.421-423
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• 2002

최근 네트워크가 실시간, 멀티미디어, 멀티캐스팅의 지원을 필요로 함에 따라 인터넷 QoS에 대한 요구 사항이 증대되고 있다. 최선형의 전달 서비스로는 이러한 응용을 지원할 수 없기 때문에 QoS 증대를 위한 IntServ(Integrated Service) 구조가 제안되었고, 또한 IntServ의 확장성 문제에 따른 DiffServ(Differentiated Service) 구조가 제안되었지만 존재하는 네트워크 환경에서 QoS 기준을 만족하기에는 부족한 실정이다. 이에 따른 인터넷 QoS 보장을 위한 구조로 DiffServ 구조와 IntServ 구조를 연동하는 방안에 대한 연구가 활발하게 진행되고 있다. 본 논문에서는 IntServ의 한계에 따른 DiffServ의 출현 배경 및IntServ와 DiffServ의 차이점을 살펴보고, 현실 가능한 DiffServ망에서의 QoS 향상을 위한 효율적인 자원예약 메커니즘을 소개하고, DiffServ와 IntServ의 연동 방안에 관한 문제점과 해결방안을 모색하고, 향후 방향을 제시하고자 한다.

• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.406-409
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• 2003

본 논문에서는 인터넷 QoS(Quality of Service)보장을 위하여 제안된 Diff-Serv(Differentiated Service)모델을 구현하고, QoS 를 보장하지 않는 BE(Best Effort)서비스와 우선 순위가 높은 패킷을 처리하여 QoS 를 보장하는 EF(Expedited Forwarding) 서비스의 차이를 통하여 Diff-Serv 망의 우수성을 입증하고자 한다. Diff-Serv 망은 BB(Bandwidth Broker)와 에지라우터 그리고 다수의 코어라우터로 구성된다. BB 로부터 라우터에 QoS Policy를 전송하기 위하여 COPS(Common Open Policy Service) 프로토콜을 구현하였으며, 사용자와 BB 사이의 SLAT/RAR(Service Level Agreement/Resource Allocation Request)를 처리하기 위하여 Admission Control 이라는 명명한 자체 프로토콜을 개발하였다. 구현된 Diff-Serv 망에서 QoS 보장 테스트를 위하여 19.2Mbps 대역폭이 요구되는 HDTV 스트리밍 서비스를 이용하여 인위적으로 Background Traffic 을 발생시켰을 때, BE 서비스만을 지원하는 망에서는 현저하게 서비스의 질이 떨어지는 반면에 Diff-Serv 망에서는 QoS가 보장됨을 알 수 있었다.

• ETRI Journal
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• v.24 no.1
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• pp.43-55
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• 2002

This paper proposes a flow-based admission control algorithm through an Asynchronous Transfer Mode (ATM) based Multi-Protocol Label Switching (MPLS) network for multiple service class environments of Integrated Service (IntServ) and Differentiated Service (DiffServ). We propose the Integrated Packet Scheduler to accommodate IntServ and Best Effort traffic through the DiffServ-aware MPLS core network. The numerical results of the proposed algorithm achieve reliable delay-bounded Quality of Service (QoS) performance and reduce the blocking probability of high priority service in the DiffServ model. We show the performance behaviors of IntServ traffic negotiated by end users when their packets are delivered through the DiffServ-aware MPLS core network. We also show that ATM shortcut connections are well tuned with guaranteed QoS service. We validate the proposed method by numerical analysis of its performance in such areas as throughput, end-to-end delay and path utilization.

• ETRI Journal
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• v.26 no.1
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• pp.27-37
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• 2004

The architecture in a differentiated services (DiffServ) network is based on a simple model that applies a per-class service in the core node of the network. However, because the network behavior is simple, the network structure and provisioning is complicated. If a service provider wants dynamic provisioning or a better bandwidth guarantee, the differentiated services network must use a signaling protocol with QoS parameters or an admission control method. Unfortunately, these methods increase the complexity. To overcome the problems with complexity, we investigated scalable dynamic provisioning for admission control in DiffServ networks. We propose a new scalable $qDPM^2$ mechanism based on a centralized bandwidth broker and distributed measurement-based admission control and movable boundary bandwidth management to support heterogeneous QoS requirements in DiffServ networks.

• The Journal of Information Technology
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• v.4 no.3
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• pp.87-100
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• 2001

IETF has proposed integrated services model(Int-Serv) and differentiated service(Diff-Serv) to supply IP QoS in Internet[1][2]. Int-Serv model uses state information of each IP flow, so satisfies QoS according to traffic characteristics, but increases the amount of flow state information with increasing flow number. Diff-Serv uses PHP(Per Hop Behaviour) and there are well-defined classes to provide differentiated traffics with different services according to delay and loss sensitivity. Diff-Serv model can provide diverse services in Internet because of having no the state and signal information of each flow. As MPLS uses the packet forwarding technology based on label, it implements the forwarding engine of high performance easily. The MPLS can set up the path having different and variable bandwidth and assign each path to particular CoS (Class of Service). Therefore it is possible to support the Diff-Serv model of well- defined classes that can provide the differentiated traffic with different services according to delay and loss sensitivity in IP QoS models of IETF. In this paper we propose a scheme that can accommodate Diff-Serv model to provide QoS. The system performance has been estimated by scheduling plan according to traffic classes.

• Journal of Communications and Networks
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• v.9 no.1
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• pp.84-92
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• 2007

This paper deals with the creation of multicast trees in a differentiated services (DiffServ) domain. Initially, we model the integration problems of multicast & DiffServ and give a general de-scription of our framework for multicast provisioning in DiffServ domains. Within this framework, we introduce a novel heuristic algorithm which calculates the multicast trees efficiently. The multicast tree's format and the bandwidth constraints per service class are modeled. The heuristic is based on the Dijkstra's shortest path algorithm and aims to produce the cheapest possible trees (Steiner tree problem) that conform to the defined model. The produced trees can be considered as DiffServ-customized Steiner trees. Furthermore, we evaluate the algorithm with theoretical and experimental analysis and finally, we present our conclusions.