全光分波多工封包交換都會環狀網路之光標頭處理及存取控制系統的設計與實現

Abstract

下一世代全光都會型網路(metropolitan area networks; MANs)旨在支援各類型要求高頻寬之網路應用程式以及訊務特性趨於動態變化之網路應用程式，全光封包交換技術(optical packet switching; OPS)，能夠滿足此類網路之需求，被視為是未來全光都會網路的一個典範。此篇論文提出之全光標頭交換與存取控制系統(optical-header processing and access control system; OPACS) 設計與實現，是應用在全光分波多工(wavelength division multiplexing; WDM)封包交換都會環型槽狀網路。OPACS的設計具有兩項獨一無二的特色。首先， OPACS設計之內頻控制(in-band)分時多工(time division multiplexing; TDM)全光標頭訊號技術，每個訊槽包含控制標頭以及資料負載，藉由波長與時間之轉換，OPACS使所有全光平行控制標頭可在成本效益考量下，進行標頭的接收、修改、以及重送。再者，OPACS系統提出之多用途媒介存取控制(medium access control ; MAC) 設計，稱為分散式多重粒度與視窗預訂(distributed multi-granularity and multi-window reservation; DMGWR)，DMGWR的動態頻寬配置設計，特別適合應用在訊務量很高且訊務特性趨於動態變化之網路。基本上， DMGWR為了確保每個網路節點能夠公平地存取網路頻寬，要求網路節點傳送資料前必須先提出預約需求，並藉由全域分散式佇列(global distributed queue)來達到網路頻寬公平性之配置。DMGWR的多重粒度設計，讓節點可以一次預約多個訊槽。DMGWR的多重視窗設計，當節點還有資料須要傳送(如大量突發訊務)，即便節點原預約資料還未傳送完畢前，當預約次數還在系統視窗範圍(window size)內時，都能再提出新的預約需求。透過實驗模擬結果得知，相對於現存的兩種主要動態頻寬配置HORNET DQBR以及WDMA網路，OPACS可以達到更為優異的系統輸出、頻寬效率、接取延遲、公平性以及大量突發訊務適應性表現。實驗結果也顯示，全光標頭交換能夠在一完全同步的方式進行標頭的刪除與整合，證明OPACS系統的可行性。

Optical packet switching (OPS) has been considered to be a promising paradigm to support a wide range of applications with different time-varying and high bandwidth demands for future optical metropolitan area networks (MANs). This thesis presents the design of an experimental optical-header processing and access control system (OPACS) for an OPS WDM metro slotted-ring network. OPMACS is endowed with two distinctive features. First, OPMACS has been designed for a dual unidirectional slotted ring network using in-band signaling control. Each control header is in-band time-division-multiplexed with its corresponding payload within a slot. OPACS enables the optical headers across all parallel wavelengths to be efficiently received, modified, and re-transmitted by means of a wavelength-time conversion technique. Moreover, OPACS embodies a versatile medium access control (MAC) scheme, referred to as the distributed multi-granularity and multi-window reservation (DMGWR) mechanism, which is particularly advantageous for traffic of high and varying loads and burstiness. Basically, DMGWR requires each node to make reservation requests prior to transmissions while maintaining a distributed queue for ensuring fair access of bandwidth. By “multi-granularity”, each node can make a reservation of multiple slots at a time. By “multi-window”, each node is allowed to have multiple outstanding reservations within the window size. Simulation pit the OPACS network against two other existing networks, simulation results show that the OPACS network outperforms these networks with respect to throughput, access delay, and fairness under various traffic patterns. Experimental results demonstrate that all optical headers are removed and combined with the data in a fully synchronous manner, justifying the viability of the system.