乙太網路自動保護交換方法在城域乙太網路的運用

IMPLEMENTING EAPS IN THE METRO ETHERNET NETWORK

林柏堅(Po-Chien Lin)

指導教授 ： 陳建華

大同大學/電機資訊學院/通訊工程研究所/碩士(2010年)

摘要

城域乙太網路最常使用環狀拓撲。因當發生斷線或設備故障時，交換機容易在環狀拓撲上自動切換路徑。為避免傳送路徑發生迴圈，第二層備援機制可選擇乙太網路自動保護交換或快速擴展樹協議。乙太網路自動保護交換運用在環狀拓撲環境中，可實現電信等級的保護切換時間，且可改善快速擴展樹協議容易全網斷線問題，大大提高網路的可靠度。
本論文透過數台交換機設備串接以模擬城域乙太網路環境。針對網路斷線與設備故障等真實環境中經常遇到的狀況進行測試，利用測試得到的數據來驗證快速擴展樹協議收斂時間過長與容易全網斷線等缺點。經由不同數量交換機的測試與修改主節點位置測試，顯現出乙太網路自動保護交換擁有穩定且快速的路徑切換時間，可取代快速擴展樹協議運用在城域乙太網路之中。本研究亦發現大量的地址轉換協議封包將導致乙太網路自動保護交換失效。此一異常現象反應給交換機廠商後，經韌體修正已可解決。

關鍵字

乙太網路自動保護交換 ； 快速擴展樹協議 ； 城域乙太網路

並列摘要

Ring topology is most often used in Metro Ethernets due to its ability to provide alternative path when network malfunctions. To prevent looping in the ring topology, either Ethernet Automatic Protection Switching (EAPS) or Rapid Spanning Tree Protocol (RSTP) must be used for Layer 2 redundant mechanism. Compared to RSTP, EAPS can achieve carrier-grade switching times and raise the network reliability.
In this thesis, we connect several switches to emulate the operation of the Metro Ethernet and then experiment several tests involving link disconnection and equipment failure that might occurred in real networks. Both RSTP and EAPS are evaluated in our experiments. Our result shows that RSTP exhibits convergence times in order of seconds and might disconnect the whole network in some cases. Under the tests of different number of switches and different location of the master node, EAPS consistently performs better than RSTP in terms of convergence time. We also found that EAPS might fail as a result of a burst of ARP packets. This problem was reported to the switch vendor and has been solved by upgrading the switch firmware.

並列關鍵字

Ethernet Automatic Protection Switching ； Rapid Spanning Tree Protocol ； Metro Ethernet Network

參考文獻

[7] MEF 2, Requirements and Framework for Ethernet Service Protection in Metro Ethernet Networks, pp 24-25, Feb 2004

[12] IEEE 802.1D, Media Access Control (MAC) Bridges, pp 137-154,Jun 2004

[1] Philippe Morin, ”Metro Ethernet Networks Update,” 2008 . [Online]Available:http://www.nortel.com/corporate/investor/collateral/nortel_merrill_lynch_final_050808.pdf [Accessed Oct. 25, 2009].

[2] NCC, “第一類電信事業價格調整係數將自民國99年4月1日起實施,” [Online]Available:http://nccwatch.org.tw/news/20100110/55952 [Accessed Jan. 13 2010].

[3] Nan Chen, “Carrier Ethernet Annual Review,” 2009 MEF Workshop. [Online]Available:http://metroethernetforum.org/page_loader.php?p_id=716[Accessed Noc. 10 2009].