Fast Failure Detection of OpenFlow Channels
Fast Failure Detection of OpenFlow Channels
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DOI：
10.1145/2837030.2837035
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发表时间：
2015-11
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通讯作者：
Daisuke Kotani;Y. Okabe
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文献类型：
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作者：
Daisuke Kotani;Y. Okabe
我们提出了一种机制，可以在运行多个控制器的交换机和控制器中快速检测 OpenFlow 通道故障。在OpenFlow网络中，保持控制器和交换机之间的OpenFlow通道处于up状态并立即检测通道故障非常重要，以便通知诸如端口down和流表修改等事件的消息始终能够立即可靠地传递到另一端。对于控制器来说，频繁交换保活消息是不希望的，因为控制器应该处理来自交换机的许多保活消息。当除保活消息之外的其他消息的速率较低时，这将是一个很大的开销，因为控制器被迫处理许多保活消息，尽管这些保活消息不直接影响网络控制。我们提出的机制自适应地发送保持活动消息以快速检测消息是否未到达另一端，而不是检查通道是否已启动。控制器及时与其他控制器共享从交换机接收到的消息，如果其他控制器通知的消息没有通过该通道到达，则该控制器认为该通道不可用。交换机在发送端口状态消息等重要异步消息后，立即向所有通道发送keep-alive消息，如果没有收到任何响应，则认为所有通道都已down掉。评估表明，我们提出的机制将故障检测延迟减少到超时，直到收到响应为止，并且延迟的开销可以忽略不计。
We propose a mechanism to detect OpenFlow channel failures quickly in switches and controllers where multiple controllers are running. In OpenFlow networks, it is important to maintain OpenFlow channels between controllers and switches are up and to detect channel failures immediately, so that messages to notify events such as port down and modification of flow tables are always delivered to the other side surely and immediately. Exchanging keep-alive messages frequently is undesirable for controllers because the controllers should handle many keep-alive messages from switches. This would be a significant overhead when the rate of other messages than keep-alive ones is low, because the controllers are forced to handle many keep-alive messages although such keep-alive messages do not affect network control directly. Our proposed mechanism adaptively sends keep-alive messages to detect quickly that a message is not reached to the other side, instead of checking whether a channel is up. A controller shares a message received from a switch with other controllers in a timely manner, and the controller regards a channel has been unavailable if the message notified by other controllers has not arrived via the channel. A switch sends keep-alive messages to all channels just after sending an important asynchronous message such as a port status message, and regards all channels have been gone down if the switch does not receive any response. The evaluation shows that our proposed mechanism reduces failure detection delay to timeout until receiving a response, and that overhead on latency is negligible.