광 버스트 스위칭 기반의 링 망에서 다중 토큰 기반 MAC 프로토콜 설계 및 성능평가

다국어 초록 (Multilingual Abstract)

With the explosion of data traffic due to tremendous user population on Internet, the need for a transmission medium with the bandwidth capabilities for handling vast amount of information in applications such as remote backup, database transfer and multimedia file sharing is highly important. Looking into the not-so-distant future, it is clear that IP data traffic will continue to scale at a quick pace. Ultimately, metro networks will be forced to scale to capacities beyond 1 Tb/s. Thus, a new architecture will be necessary to deliver greater than 1 Tb/s capacity while still allowing network operators to compete in the cost-sensitive market.
Under these circumstances, Optical Burst Switching (OBS) has been proposed as today’s viable solution to close the gap between the vast bandwidth available in Wavelength Division Multiplexed (WDM) networks and the much smaller traffic load offered by individual end-users. In OBS, packets are electronically buffered at the aggregation nodes, assembled into bursts, and transmitted all-optically throughout the core network as a single burst. Generally, buffering of the burst at the intermediate nodes is not provided. The advantage of OBS is that it provides statistical multiplexing at the optical layer with relaxed switching constraints (when compared to packet switching). Compared with optical circuit switching, it provides efficiency and scalability by statistical multiplexing of bursts.
Most OBS has been studied in wide area networks (WANs) with the mesh topology. But in the case of metropolitan area networks (MANs) which are serving as a backbone that interconnects a number of access networks, ring topologies are commonly chosen due to its simplified management, well-established protection mechanisms against network failure, and compatibility with existing metro infrastructures, such as Synchronous Optical Network/Synchronous Digital Hierarchy (SONET/SDH) rings. Recently, a use of OBS technology for ring networks has been proposed by Xu et al [3].
The present metro network has mainly formed with ring topology, and is migrating to the high-speed WDM network. In this paper, we present OBS WDM Ring architecture for supporting Metropolitan Area Networks (MAN). The OBS ring network consists of N OBS nodes connected by optical fiber, which support N data burst wavelengths and a separate control wavelength. There are a pair of tunable transmitter and tunable receiver (TT-TR) for data burst wavelengths and a pair of fixed transceiver for a control wavelength in each node. Under this architecture, we designed a MAC protocol to use resources efficiently.
The designed MAC protocols are based on multi-token so as to reduce an excessive processing overhead while avoiding wavelength collision in OBS nodes. In order to implement this, we designed the CA(Collision Avoidance) protocol. Also, we designed the IR(Immediate Release) to improve performance of CA. The CA and IR make use of three algorithms, T-RR(Token-Round Robin), DR-EFT(Delay Reservation-Earliest Free Time) and TR-EFT(Token Release-Earliest Free Time). For performance evaluation of the proposed MAC protocol, simulations were performed in the view of burst loss rate, average packet delay, wavelength utilization and fairness. As the result of the simulations, CA shows resonable performance in terms of burst loss rate and throughput. And IR represents high channel utilization and low packet delay compared to CA. Additionally, we confirmed that T-RR and DR-EFT guarantee fairness in terms of throughput, packet delay.

목차 (Table of Contents)

• 목차
• 그림목차 = ⅲ
• 표목차 = ⅳ
• 약어표 = ⅴ
• ABSTRACT = ⅵ
• Ⅰ. 서론 = 1
• Ⅱ. 링 토폴로지 기반의 광 버스트 스위칭 기술 = 4
• 2.1. 광 버스트 스위칭 기술 = 4
• 2.1.1. 일반적인 광 버스트 스위칭 = 4
• 2.1.2. Offset 시간 결정 = 6
• 2.2. 링 토폴로지 기반의 광 버스트 스위칭 기술 = 8
• 2.2.1. 광대역 메트로 망 개요 = 8
• 2.2.2. 다양한 광 버스트 스위칭 링 시스템 = 10
• 2.3. TT-TR 기반 시스템 설계 = 11
• Ⅲ. 광 버스트 스위칭 링을 위한 MAC 프로토콜 설계 및 구현 = 15
• 3.1. 기존 광 버스트 스위칭 링 문제점 분석 = 15
• 3.2. 다중 토큰 기반 MAC 프로토콜 설계 = 16
• 3.2.1. 제어 프레임 구조 설계 = 16
• 3.2.2. 버스트 손실 해결 방안 = 17
• 3.2.3. 다중 토큰 기반 MAC 프로토콜 = 18
• 3.2.3.1 CA(Collision Avoidance) 기반 MAC 프로토콜 = 18
• 3.2.3.2 IR(Immediate Release) 기반 MAC 프로토콜 = 24
• 3.3. OPNET을 이용한 다중 토큰 기반 시스템 모델 구현 = 28
• 3.3.1. 네트워크 모델 = 28
• 3.3.2. 노드 모델 = 29
• 3.3.3. 프로세스 모델 = 31
• Ⅳ. 다중 토큰 기반 MAC 프로토콜 성능 분석 = 34
• 4.1. 시뮬레이션을 위한 환경 설정 = 34
• 4.2. 제안한 프로토콜의 시뮬레이션 결과 및 성능 비교 분석 = 35
• 4.2.1. 버스트 손실률 및 처리율 = 35
• 4.2.2. 채널 이용률 = 37
• 4.2.3. 평균 패킷 지연 = 38
• 4.2.4. 각 노드의 처리율 및 큐잉 지연 관점에서의 공평성 평가 = 40
• 4.2.5. 링 크기 및 버스트 크기에 따른 성능 비교 = 42
• Ⅴ. 결론 = 47
• 참고문헌 = 49