Monitoring Dynamic Modification of Routing Information in OpenFlow Networks
Saneyasu Yamaguchi, Akihiro Nakao, Masato Oguchi, Atsuhiro Goto, Shu Yamamoto · 2016
Network routing information can be dynamically modified with ease using software-defined networking (SDN). However, it is not possible to simultaneously change the routing information in all the switches in a network. Thus, there must exist a short period in which the routing information is not completely synchronized. In such a period, some switches have the new routing information and the others have the old information. This may cause routing loops and packet losses. For discussing such issues, an integrated observation that covers all network elements is required. In current SDN networks, each network element has its own operating system and works independently. Thus, integrated monitoring and analyses is not achieved. In this paper, we focus on SDN networks using OpenFlow and propose a method for monitoring the behavior of the entire network during a period in which the network routing information changes. We construct an experimental OpenFlow network with open-source OpenFlow software. Then, we modify the software source code and implement event log storing functions for profound monitoring. Further, we create an integrated analysis system that gathers all monitored events in all the network elements and visualizes these events. We apply the proposed method and analyze the packet losses for a period in which the routing information is modified in OpenFlow SDN. The obtained results demonstrate that the cause of packet losses can be identified by our monitoring system.