• Journal of KIISE:Information Networking
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• v.29 no.1
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• pp.65-76
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• 2002

QoS routing is a routing technique for finding feasible path that satisfies QoS requirements required by application programs. Since QoS routing determines such paths in terms of dynamic network state, it satisfies the requirement of applications and increases the utilization of the network. The overhead is, however, generated by routers to exchange the information of the dynamic state of network. In order to reduce this protocol overhead, a timer based update mechanism is proposed in which router checks the change of the network status periodically and network state information is exchanged if the change is greater than a certain value. Using large update period makes, though, routing performance irresponsive to the parameters which determine the update of the network state of the router. In addition to this, large update period may result in inaccurate network state information at routers and cause resource reservation failure. The resource reservation failure generates additional overhead to cancel the resource reservation of the part of the path. In this paper, we propose mechanisms enhancing the existing network state update policy with respect to these two problems. Performance of the proposed schemes are evaluated through a course of simulation.

• Journal of KIISE:Computing Practices and Letters
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• v.6 no.4
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• pp.430-440
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• 2000

To support Integrated Services in the Internet, the Internet Engineering Task Force(IETF) has developed new mechanisms. These new mechanisms include Resource Reservation Protocol(RSVP) and Integrated Services model. RSVP and Integrated Services are independent of the underlying link layer technologies and it is necessary to define the mapping of RSVP and Integrated Services specifications onto specific link layer technologies. IETF proposed a Subnet Bandwidth Manager(SBM) providing a method for mapping RSVP onto IEEE802 style networks. However, the SBM has several constraints and problems. For solving these constraints and problems, we design and implement a new Ethernet Bandwidth Manager(EBM). This paper discusses (1) new bandwidth management mechanism independent of RSVP, (2) simulation of Ethernet bandwidth to analyze the characteristics of Ethernet and accomplish Ethernet bandwidth management, (3) design and implemetation of EBM that allows Controlled-Load Service, and (4) results of our experiments on EBM.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.05b
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• pp.1121-1124
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• 2003

최근 이동 네트워크에서 QoS(Quality of Service)를 보장하기 위해 기존의 ReSouce reserVation Protocol (RSVP) 메커니즘을 확장해서 사용하고 있다. 기존 연구들은 대게 이동 호스트의 이동을 도메인 내와 도메인간을 나누고 있다. 피러나 도메인 간 이동시에는 경계 셀의 중첩된 지역의 크기가 등록 과정과 자원 예약 과정 모두를 수행하기에 충분히 크지 않기 때문에 도메인 간 이동시 데이터 손실이 일어나 서비스 중단 현상이 발생한다. 본 논문에서는 두 개 이상의 도메인이 중첩된 지역에 위치한 그레이 셀을 도입하여 이와 같은 문제를 해결하고자 한다. 시뮬레이션 결과를 보면 제안한 프로토콜에서 이동 호스트가 도메인 간 이동을 하더라도 도메인 내에서 이동할 때와 거의 유사한 데이터 손실을 보이고 있기 때문에 도메인 간 이동 시 발생하던 서비스 중단 현상이 감소됨을 볼 수 있다.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.21-24
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• 1999

멀티미디어 시대로의 진입에 따른 인터넷에서의 실시간 데이터 전송을 위한 어플리케이션의 요구에도 불구하고 현재의 인터넷은 최선형 서비스만을 제공할 뿐 QoS(quality of service)를 제공하지 못하고 있다. 이에 인터넷 표준화 기구에서는 종합서비스(IS : integrate service)모델을 정했다. 〔5〕 그러나 기존의 shared LAN 환경에 이를 적용하기에는 자원의 공유로 인한 어려움이 있다. 반면. 직렬 버스의 표준으로 자리잡은 IEEE 1394 고속 직렬 버스〔1〕〔2〕는 예약된 대역폭을 보장할 수 있을 뿐만 아니라 고속통신이 가능하여 IS 모델의 적용에 적합한 기술이라고 할 수 있다. IS over 1394 프로토콜〔8〕은 IS 모델을 IEEE 1394 고속 직렬 버스에 적용하기 위한 프로토콜로써 본 논문에서는 이의 구현을 위한 구조를 고찰하였다.

• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.269-272
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• 2003

Ad hoc 네트워크에 대한 상업적인 관심이 지속적으로 증가함에 따라, 최근 Ad hoc 네트워크에 QoS (Quality of Service)를 지원하기 위한 많은 연구가 이루어지고 있다. 지금까지의 연구는 대부분 QoS 기반 라우팅 프로토콜과 자원 예약 (resource reservation) 그리고 QoS MAC (Medium Access Control) 프로토콜에 관한 것이었다. Ad hoc 네트워크에 QoS를 제공하기 위해서는 위의 요소들이 상호 협력하여 동작하고 Ad hoc 네트워크의 특성이 충분히 고려된 005 모델에 관한 연구가 절실히 필요하다. 본 논문에서는 Ad hoc 네트워크에서 종단 사용자간 (end-to-end) 005를 제공하기 위한 서비스 모델의 설계와 구현방법에 대해 제안하였다.

• Journal of KIISE:Information Networking
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• v.29 no.6
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• pp.722-737
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• 2002

As the number of multimedia applications increases, various protocols and architectures have been proposed to provide QoS(Quality of Service) guarantees in the Internet. Most of these techniques, though, bear inherent contradiction between the scalability and the capability of providing QoS guarantees. In this paper, we propose a protocol, named DQSP(Dynamic QoS Support Protocol), which provides the dynamic resource allocation and admission control for QoS guarantees in a scalable way. In DQSP, the core routers only maintain the per source-edge router resource allocation state information. Each of the source-edge routers maintains the usage information for the resources allocated to itself on each of the network links. Based on this information, the source edge routers perform admission control for the incoming flows. For the resource reservation and admission control, DQSP does not incur per flow signaling at the core network, and the amount of state information at the core routers depends on the scale of the topology instead of the number of user flows. Simulation results show that DQSP achieves efficient resource utilization without incurring the number of user flow related scalability problems as with IntServ, which is one of the representative architectures providing end-to-end QoS guarantees.

• The KIPS Transactions:PartC
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• v.9C no.2
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• pp.283-292
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• 2002

This paper develops a scheme of resource management for guaranteeing QoS of realtime traffic in wireless mobile internet environments Mobile terminal has significant impact on the QoS originating mobility provided to a real-time application. The currently proposed MRSVP is not clear the boundary of resource reservation tregion and also can give rise to signal overhead to maintain sessions. To solve above problem, we propose the new reservation protocol, mobile cluster based H-MRSVP to combine MRSVP with moving cluster concept. In this paper, we analytically design our model for guaranteeing the QoS of realtime traffic and compare the three schemes: guard channel allocation schemes, DCA and our model. The performance measures are the probabilities of new call blocking, handoff dropping, resource utilization and service completion versus the system offered Erlang load. Consequently, Simulation indicate our model is more flexible than DCA in a view pint of channel utilization and gains the advantage over guard channel scheme with respects to the mobility.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.1342-1345
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• 2007

현재 NGN 망에서 강조되는 QoS 보장 기술은 인터넷에서 QoS(Quality of Service) 제공을 위해 해당 응용 서비스 마다 자원을 예약하거나 할당하는 기능을 수행하며, 이 때, 효율적인 종단간의 QoS 보장을 위해서는 전체적으로 자원관리를 할 필요가 생긴다. 정책(Policy) 기반 QoS 기술 관리는 이 경우에 수행이 된다. NGN 망에서의 정책 기반 QoS 기술을 위해서는 정책 기반 QoS 관리 기술 구조 및 프로토콜에 대한 총괄적인 이해가 우선되어야 한다. 즉, 정책 결정 및 정책 실행과 관련한 정책 기반 QoS 관리 기술 구조와 프로토콜 관련한 COPS(Common Open Policy Service)와 LDAP(Light Weight Directory Access Protocol)을 중심으로 이해가 되어야 하고, 이를 토대로 해서 정책 기반 QoS 관리 기술 서비스가 제공 될 수 있다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.4C
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• pp.273-281
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• 2002

Recently, demand for real-time data and multimedia data is rapidly increasing, and it is impossible for mobile Ad Hoc networks with only best effort service to efficiently transfer such data. So, we absolutely need the QoS service which reserves the communication resources in advance. The existing routing protocols, which assume that the links between nodes are bidirectional, provide the convenience for the route discovery and maintenance, but can not support the routing function for the unidirectional links due to the wireless link property easily changing with time under the real wireless environment. In order to solve such problems, in this dissertation we suggested a unidirectional QoS routing a waste of communication resources. The waste of protocol that supports unidirectional links and reduces communication resources is reduced by establishing the shortest route suitable to QoS support, considering in advance the usable communication resources at each node.

• The KIPS Transactions:PartC
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• v.11C no.6 s.95
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• pp.815-820
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• 2004

For providing high quality-guaranteed service over Internet, traffic engineering based on an MPLS technology is being introduced. MPLS traffic engineering performs the computation on the path guaranteeing service`s quality and the reservation on network resources by an MPLS signaling protocol. As one of MPLS signaling protocol, RSVP-TE protocol transmits and receives periodic refresh messages for maintaining the path of a traffic flow. Such characteristic gives a heavy processing overhead to routers for maintaining states of large number of paths. In this paper, we propose a scalable implementation approach for RSVP-TE without dramatically increasing processing overhead. And we eval-uate the processing overhead on periodic messages by implementing the RSVP-TE protocol and the reduction mechanism of periodic messages.