利用網域名稱系統的協助，設計適合應用層群播之行動支援機制

Mobility Supporting for DNS-aided Application Layer Multicast

吳瑞益(Rui-Yi Wu)

指導教授 ： 楊峻權

國立暨南國際大學/科技學院/通訊工程研究所/碩士(2010年)

https://doi.org/10.6837/NCNU.2010.00029

摘要

Internet已成為今日不可或缺的重要技術，隨著網路多媒體技術的發展，為了有效率使用網路進行多點傳輸的工作，因而出現了群播技術，傳統上只有網路層才支援的群播技術，但在現實網路大環境上遭遇許多限制(e.g. 路由器,管理者因素,etc.)而無法快速被應用在網路上，開始出現應用層群播技術(ALM, Application Layer Multicast)。
應用層群播會透過應用層的軟體系統來進行資料傳送，當資料傳送到網路層時，由於網路分層協定獨立運作下，還是以單點傳輸的模式，所以相對於網路層，會有重覆性的資料及更大的傳輸延遲現象，為了取更好的應用層群播效能，大部份的應用層群播協定會透過網路探測的方式詴圖取得網路實體架構，也導致協定的維護成本節節上升。
網域名稱命名系統(DNS)為今日廣泛使用於網路環境中的應用層網域名稱解譯機制，而且取得方便，所以在DNS-ALM中，便藉由這樣的技術可以很容易建構相當貼近網路實體環境的應用層群播機制，卻無頇耗費太多成本。
隨著行動網路的發展，有越來越多使用者以行動網路連上Internet，但是行動使用者具有無法預測的換手(Handoff)可能性，若是應用層群播機制中有行動使用者存在，為了維持穩定的群播效能，勢必對行動成員做額外處理，本論文考量ALM上的效能及穩定性，延伸階層式ALM-tree之架構，提出具有Supply Cache及Spiral Link
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機制的M-ALM，目的是為了讓存在行動網路使用者也能享有高效率的應用層群播服務。

關鍵字

網域名稱命名系統 ； 應用層群播機制 ； 行動

並列摘要

Owing to computer technologies development, there are many multimedia services and applications appearing via Internet. How to provide higher speed and lower waiting time Internet service for end users is an important research issue. Traditionally, network layer scheme of IP multicast can decrease transmission delay and increase bandwidth utilization. Due to network management issue and scalability problem, these have hampered the widespread deployment of IP multicast in the global Internet. So the Application Layer Multicast (ALM) approaches operate through the overlay network and recently proposed as a viable alternative solution to IP multicast. Considering transmission performance, ALM approach should construct an application layer topology as close to network layer topology for multiple user data transmission. We apply the previous scheme of DNS-aided ALM which builds overlay network with the help of the existing Domain Name Service (DNS). Furthermore, the wireless network also popularizes in the Internet, the mobile users might make some new problems in ALM topology (e.g. ALM tree or mesh isolation). So we try to modify the establishment rule of
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DNS-aided ALM hierarchy overlay network and propose the Supply Cache and Spiral Link mechanisms for mobility supporting in ALM environment. The simulation study shows that the proposed mechanisms have better performance in contrast scheme.

並列關鍵字

ALM ； Mobility ； DNS

參考文獻

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[4] Y. Chu, S. G Rau et al., “A Case for End System Multicast,” Proceedings of the ACM international conference on Measurement and modeling of computer systems (SIGMETRICS), pp. 1-12, June. 2000.

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