- 學位論文
即時性封包的重新排程於光纖環狀接取網路上
Real-Time Packet Rescheduling in WDM Ring Access Network
若您是本文的作者，可授權文章由華藝線上圖書館中協助推廣。
摘要
全光網路(All Optical Network)解決即時性封包通訊中網路頻寬的不足並且增加傳輸速率的關鍵技術。其中以波長分割多工(Wavelength Division Multiplexing，WDM)為最主要的技術，它不僅大大地提昇骨幹傳輸網路的頻寬、降低網路費用及網路傳輸控制的維護趨於簡單。然而，在高速網路上探討具有服務品質(Quality of Service，QoS)即時性(Real-Time)封包的傳送是一項重要的議題。本論文藉由記號(Token)的運用來保持整個環狀接取網路(Ring Access Network)資訊的一致性，並提及封包重新排程(Rescheduling)的方法來盡量達到其即時性封包的QoS，有記號的節點才能作重新排程動作，而沒有記號的節點只能傳送、接受及轉送資料。在此利用Priority-Differentiated Scheduling (PDS)演算法來處理即時性封包的問題，允許高優先權的即時性封包可以插隊到事先已排程好的低優先權的非即時性封包前傳送。本文結合兩個波長頻道選擇演算法來配合PDS演算法，稱為PEM (PDS-EAC-MTD)演算法，其中EAC (Earliest Available Channel)演算法應用於即時性封包的傳送，此演算法建立一條給即時性封包傳送的路徑。而另一個MTD (Minimum Time Difference)演算法應用於非即時性封包的傳送，其目的是節省非即時性封包傳送頻道的使用率並給予即時性封包較快速建立傳送路徑。模擬結果顯示在固定存取節點與固定頻道數而改變流量負載或是在固定存取節點與固定流量負載而改變頻道數下，PEM演算法所得到的平均延遲時間均比其他三者演算法(NPEM演算法、PEE演算法與EATS演算法)還來得好，而在固定存取節點與頻道數不同的情況下，含有MTD演算法者所測得的平均頻道使用率(Channel Utilization)會比不含MTD演算法者還來得高。
並列摘要
All optical networks have solved the problem of bandwidth insufficiency in the communication network and key technical issue of increasing the transmission speed. The most important technique is Wavelength Division Multiplexing (WDM). It is not only increases the bandwidth of backbone transmission network significantly, but also decreases the network cost and makes the controlling and maintaining of transmission easy. However, it is an important issue to achieve real-time packets quality of service (QoS) on the high speed Internet. This paper uses token to maintain the information of whole Ring Access Network consistent, and it uses the rescheduling algorithm to achieve the QoS of real-time packets. The node only has the token is able to reschedule, while the rest nodes can only transmit, accept, and send information. We adopt the Priority-Differentiated Scheduling (PDS) algorithm to deal with the problem of real-time packets, and allow real-time packets with the high priority to get transmission first to insert the front line of the scheduling unreal-time packets with low priority. This paper combines two algorithms that are used to select wavelength and PDS algorithm to form PEM (PDS-EAC-MTD) algorithm. Within this, the Earliest Available Channel (EAC) algorithm is used for the transmission of real-time packets. It establishes the transmission path for real-time packets. The Minimum Time Difference (MTD) algorithm is used for the transmission of nonreal-time packets to save the channel utilization and let the path of real-time packets establish the path quickly. The simulation results show that as the access nodes and the number of channels are fixed, whereas traffic load and the number of channels are varied, the average delay time resulted from PEM algorithm is shorter than the other three algorithms (NPEM, PEE, and EATS). And when the access nodes are fixed and the number of channels is different, the channel utilization derived from algorithms with MTD is higher than those without MTD.
參考文獻
[1] R. Gaudino, M. Len, G. Desa, M. Shell, and D.J. Blumenthal, “MOSAIC: A Multiwavelength Optical Subcarrier Multiplexed controlled Network,” IEEE J. Select. Areas in Commun., Vol. 16, No. 7, pp. 1020-1027, Sep. 1998.
[2] J.R. Kiniry, “Wavelength division multiplexing: ultra high speed fiber optics,” IEEE Internet Computing Volume: 2, Page(s): 13-15, March-April 1998.
[3] P.L. Chu and J. Diao, “Packet rescheduling in WDM star networks with real-time service differentiation,” Lightwave Technology, Journal of, Volume: 19, Issue: 12, Page(s): 1818—1828, Dec 2001.
[4] N. Takachio, H. Suzuki, M. Fujiwara, Jun-ichi Kani, K. Iwatsuki H. Yamada, T. Shibata and T. Kitoh, “Wide Area Gigabit Access Network Based on 12.5 GHz Spaced 256 Channel Super-dense WDM Technologies,” Electronics Lett., Vol. 37, No. 5, pp. 309-311, Mar. 2001.
[7] F. Jia, B. Mukherjee and J. Iness, “Scheduling variable-length messages in a single-hop multichannel local lightwave network,” IEEE/ACM Transactions Networking, Vol. 3, pp. 477-488, Aug 1995.