在OVS創建patch ports，用於連接兩個bridge

OVS通過在不同的bridge上面創建patch ports，將兩個bridge連接起來。比如，OpenStack里面的br-int和br-tun。

在bridge上創建patch port的命令主要是下面三條。

在兩個bridge里面創建一對ports，並互相指定peer，就實現了兩個網橋連接。命令如下：

ovs-vsctl add-port <bridge name> <port name>  
ovs-vsctl set interface <port name> type=patch  
ovs-vsctl set interface <port name> options:peer=<peer name>  

兩個網橋分別配置patch port完成后，查看狀態如下：

# ovs-vsctl show

    Bridge "br2"
        Port "br2"
            Interface "br2"
                type: internal
        Port "br2--br0"
            Interface "br2--br0"
                type: patch
                options: {peer="br0--br2"}
    Bridge "br0"
        Port "bond0"
            Interface "eth0"
            Interface "eth2"
        Port "br0--br2"
            Interface "br0--br2"
                type: patch
                options: {peer="br2--br0"}
        Port "br0"
            Interface "br0"
                type: internal