关键词: OpenFlow网络, OpenFlow协议, 控制报文, UDP流, 控制器

Abstract: The data plane of OpenFlow networks sends packets which don’t match any flow entry to the controller, and in such case connectionless burst traffic is encapsulated as control messages, until the data plane receives a response message from the controller. This process produce redundant control messages for both the control and data planes, which influences the performance of the entire network. However, current OpenFlow protocol doesn’t give definite explanation or handle this problem. In this paper, we propose two approaches of eliminating redundant control messages on the control plane (referred as ERCMC) and on the data plane (referred as ERCMD). ERCMC constructs latest packet-in message view (referred as LPMV) on the controller to mark the latest packet-in messages, so as to eliminate redundant control messages on the control plane. ERCMD adds marks directly on the data plane, so that the burst packets are directly buffered and never encapsulated as control messages. We implement these two approaches in NOX and Open vSwitch respectively, and evaluate the performance of the two approaches. The results of our experiments show that ERCMC can eliminate redundant control messages, but it will add extra processing overheads; ERCMD can not only eliminate redundant control messages, but also alleviate the load of the controller and OpenFlow switches.

Key words: OpenFlow network, OpenFlow protocol, control messages, UDP flow, controller