ovs-ofctl：version negotiation failed (we support version 0x01, peer supports version 0x04)

查看Open vSwitch中的流表时出错。

sudo ovs-vsctl dump-flows s1

2018-03-08T06:23:42Z|00001|vconn|WARN|unix:/var/run/openvswitch/s1.mgmt: version negotiation failed (we support version 0x01, peer supports version 0x04)
ovs-ofctl: s1: failed to connect to socket (Broken pipe)

错误原因：

默认协议版本为OpenFlow10

解决办法：

sudo ovs-ofctl -O OpenFlow13 dump-flows s1

添加-O OpenFlow13指定协议版本。