針對OSPF網路的快速偵測錯誤方法

Abstract

在OSPF網路中路由器是透過HELLO協定去得到周遭相鄰路由器的資訊。在標準的OSPF設定之下，網路的路由表通常需要花費數十秒的時間才能收斂。而HelloInterval值的大小深深影響著錯誤偵測的時間長短，因此我們可以透過縮短HelloInterval的值來加速錯誤偵測的時間。而合適的HelloInterval的值會受到一些網路環境變數的影響，例如：網路的大小，網路壅塞的程度…等等。然而，用人為的方式去設定合適的HelloInterval相當沒效率，因此我們採用動態且自動的方式去調整HelloInterval並去取代原始的OSPF設定。透過模擬結果可以觀察出錯誤偵測的時間以及網路收斂的時間都有所改善。

In OSPF networks, the routers use Hello protocol to get neighbor’s information. With default settings of standard OSPF protocol, the network usually takes several ten seconds to detect a failure. The value of HelloInterval influences the failure detection time highly; therefore, we want to shorten the HellonInterval to achieve faster failure detection. The suitable value of HelloInterval depends on several network environment parameters, such as network size, network congestion level and so on. However, it is not efficient to adjust the value of HelloInterval manually. We design an adaptive HelloInterval adjustment method which can adjust HelloInterval automatically to replace default setting in OSPF protocol. Simulation results show that the proposed method can accelerate the failure detection time and improve the network convergence time. And it can be easily applied to OSPF networks without any setting of HelloInterval.