• Journal of Internet Computing and Services
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• v.6 no.3
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• pp.97-106
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• 2005

Generally, network QoS is determined by timeliness, bandwidth, and reliability, As IT technologies are growing day by day, the bandwidth and reliability factors are expected to be able to satisfy user's requirements. The timeliness factor, however, has not fully met user's requirements yet. In this paper, we propose a packet forwarding scheme named POSIA (Packet forwarding Scheme based on Interworking Architecture) that can provide quite a good QoS (quality of service) by minimizing processing time which is the major part of the timeliness factor. Based on path and resource reservation mechanism, the proposed POSIA makes routers on the packet forwarding path synchronize with each other and then forward packets, The POSIA has been verified to outperform the existing MPLS packet forwarding scheme through computer simulations using OPNET.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.10b
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• pp.1477-1480
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• 2001

기존 통신사업자가 급변하는 통신시장에 대응하기 위한 구체적 접근방법에 초점을 맞추어 통신기술의 변화와 이에 따른 기존망을 어떻게 개선하여야만 수익성에 차질을 빚지 않을 수 있느냐가 전재 조건이 된다. 먼저 통신기술의 변화에 따른 망의 진화방향을 음성의 패킷화 실현, 망 구조의 단순화 및 통합화를 통한 운용비용의 절감, 향후 신규서비스의 수용에 용이한 방향이 있어야 한다. 본 논문에서는 ATM을 중심으로 한 차세대 교환망에서 음성과 데이터가 동일 패킷망을 사용하므로서 망 대역폭을 효율적으로 활용하는 방법과 유효 대역 사용률을 향상하는 유연한 대역관리 방법에 대해 개괄적으로 논하였으며, 이를 바탕으로 대역폭 할당 프로토콜을 분석한 수 있는 모델을 제안하고, 주어진 음성 및 데이터 트래픽의 요구와 제약을 조건으로 시스템 파라미터를 최적화하기 위해 update interval 시간과 음성과 데이터 트래픽에 예약된 슬롯의 수를 사용하였다. 분석적인 모델은 성능에 관한 트래픽 유형들의 영향뿐만 아니라 혼합 트래픽 시스템의 동적 할당 방법과 대역관리 방법을 제공한다.

• The Journal of Korean Association of Computer Education
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• v.7 no.1
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• pp.37-44
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• 2004

Differentiated services network (DiffServ) aims to provide the same service to a group of connections that have similar Quality of Service requirements. One of the essential function to realize DiffServ is the traffic conditioning mechanism. The paper proposes the enhanced traffic conditioning mechanism which can assure the reserved rates of TCP and UDP flows and support fair distribution of excess bandwidth. The simulation results show that the new mechanism is rather insensitive of the effect of UDP against TCP throughput, and performs better both in terms of throughput assurance and fair distribution of excess bandwidth in case of well-provisioned and over-provisioned network environment.

• The KIPS Transactions:PartC
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• v.14C no.1 s.111
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• pp.81-86
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• 2007

New multimedia services over the cellular/WLAN overlay networks require different Quality of Service (QoS). Therefore, efficient network management system is necessary in order to provide QoS sensitive multimedia services while enhancing network performance. In this paper, we propose a new online network management scheme that implements bandwidth reservation, congestion and transmission control strategies. Our online approach to network management exhibits dynamic adaptability, flexibility, and responsiveness to the current traffic conditions in multimedia overlay networks. Simulation results indicate the superior performance of our proposed scheme to strike the appropriate performance balance between contradictory QoS requirements under widely varying diverse traffic loads.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.04a
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• pp.479-482
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• 2001

인터넷에서 이질적인 QoS(Quality of Service)를 보장하기 위한 현재까지의 연구는 크게 망 차원에서의 자원 예약방법과 계층적 멀티캐스트를 이용한 적응 방법으로 구분된다. 첫번째 방법의 경우 RSVP(resource ReSerVation Protocol) 시그널링을 사용하므로 정량적인 QoS 보장은 가능하나 각 라우터에서 각 세션 플로우 상태 정보를 유지해야 하는 확장성 문제점이 있다. 두번째 방법의 경우 계층적 인코딩을 사용하여 응용 플로우를 여러 계층의 서브스트림으로 분리하고 각각을 멀티캐스트 채널을 통하여 전송한다. 그러나 이 메커니즘은 라우터가 각 계층간의 중요도를 인식할 수 없을 뿐만 아니라 멀티 캐스트 그룹 관리와 주소 할당 문제에 있어서 복잡성을 가진다. 본 논문에서는 제안된 메커니즘들의 문제점을 해결하고자 계층적 인코딩에 의해 생성된 스트림들간의 차별화를 통해 라우터에서 대역폭이 부족한 수신자에게는 기본적인 품질의 스트림만을 제공하는 반면에 대역폭이 충분한 수신자에게는 최상의 품질을 제공할 수 있는 이질적 QoS 방안을 제안한다.

• The KIPS Transactions:PartC
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• v.13C no.2 s.105
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• pp.203-210
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• 2006

Fair packet scheduling algorithms supporting quality-of-services of real-time multimedia applications can be classified into the following two design schemes in terms of the reference time used in calculating the timestamp of arriving packet: Finish-time Design (FD) and Start-time Design (SD) schemes. Since the former can adjust the latency of a flow with raising the flow's reserved rate, it has been applied to a router for the guaranteed service of the IETF (Internet Engineering Task Force) IntServ model. However, the FD scheme may incur severe bandwidth loss for traffic flows requiring low-rate but strong delay bound such as internet phone. In order to verify the usefulness of the SD scheme based router for the IETF guaranteed service, this paper analyzes and compares two design schemes in terms of bandwidth and payload utilizations. It is analytically proved that the SD scheme is better bandwidth utilization than the FD one, and the simulation result shows that the SD scheme gives better payload utilization by up to 20%.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.4B
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• pp.444-454
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• 2004

To support diverse transmission requirements of multimedia applications, Quality of Service (QoS) should be provided in the Internet, where only the best-effort service is available. In this paper, we describe our recent effort on the implementation and verification of an extendable and flexible QoS allocation and resource management system based on the bandwidth broker model for realizing the IETF differentiated service (DiffServ). Focusing on the bandwidth issue over single administrative domain, the implemented system provides real-time resource reservation and allocation, delayed call admission control, simple QoS negotiation between sewer and users, and simple resource monitoring. The implemented system is verified by evaluating the performance of a resource-intensive application over the real-world testbed network.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.3
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• pp.351-355
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• 2010

The service which is required wide bandwidth is growing in these days, so building up High Speed communication system is being required. The Task Force team of IEEE 802.3ah set the EPON as a standard; next generation subscriber access network. For offering a high quality service, 10G EPON that is changed from 1Gbps uplink downlink bandwidth to 10Gbps is come up. Although Kramer had studied 10G EPON there was a QoS limitation, when load is low, End-to-End maximum delay is increased. This paper is suggesting time synch ronization method, resource reservation method, band width allocation method. We confirmed that 10EPON was able to offer quality service by the result of the OPNET.

• Journal of Korea Society of Industrial Information Systems
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• v.15 no.2
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• pp.31-39
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• 2010

VoD(Video-on-Demand) servers have to provide timely processing guarantees for continuous media and reduce the storage and bandwidth requirements for continuous media. The compression techniques make the bit rates of compressed video data significantly variable from frame to frame. A VoD system should be able to provide the client with interactive operations such as fast forward and fast rewind in addition to normal playback of movie. However, interactive operations require additional resources such as storage space, disk bandwidth, memory and network bandwidth. In a stored video application such as VoD system, it is possible that a priori disk access patterns can be used to reserve the system resources in advance. In addition, clients of VoD server spend most of their time in playback mode and the period of time spent in interactive mode is relatively small. In this paper, I present the new buffer management scheme that provides efficient support for interactive operations in a VoD server using variable bit rate continuous media. Simulation results show that our strategy achieves 34% increase of the number of accepted clients over the LRU strategy.

• Proceedings of the Korea Information Processing Society Conference
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• 2006.05a
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• pp.1207-1210
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• 2006

다양한 유 무선 통신 환경에서 사용되는 많은 종류의 사용자 단말은 프로세싱 능력과 가용 대역폭의 한계 등의 제한된 성능이 있지만 사용자는 일반 PC와 같은 성능의 응용 서비스를 요구한다. 하지만 서비스 제공자는 모든 단말 종류에 맞는 서비스를 제공하기 힘들다. 본 논문에서는 사용자 환경과 단말의 성능을 고려하지 않고, 전달 망의 자원 예약만으로 서비스를 제공하는 경우의 문제점을 개선하는 서비스 제어 관리자를 제안한다. 서비스 제어 관리자는 사용자 환경과 단말 능력에 맞는 서비스를 제공하기 위해서 서비스 품질 협상을 수행한다. 또, SIP 프락시 기능을 가지고 기존에 제안된 SIP 프로토콜 기반 서비스 제어 관리자들과의 연동한다. 이 때, 서비스 제공 과정에서 효율적으로 메시지를 전달하기 위해 새롭게 SIP 헤더를 제안한다.