功能用增加中间层的方案来解决。
仿佛回到用交换机和路由器模拟器的感觉。
遇到执行命令小问题，狗哥搞定：
mininet>
mininet> dpctl dump-flows tcp:127.0.0.1:6634
*** s1 ------------------------------------------------------------------------
dpctl: field tcp:127.0.0.1:6634 missing value
mininet>
mininet> dpctl add-flow tcp:127.0.0.1:6634 in_port=1,actions=output:2
*** s1 ------------------------------------------------------------------------
dpctl: 'add-flow' command takes at most 2 arguments
mininet>
Comment: Currently, Mininet console does not allow you to run all the dpctl commands. To fully utilize dpctl command, use SSH terminal. Or specify switch name in front, e.g.,
mininet> s1 dpctl add-flow tcp:127.0.0.1:6634 in_port=1,actions=output:2 mininet> s1 dpctl dump-flows tcp:127.0.0.1:6634 stats_reply (xid=0x623ead81): flags=none type=1(flow) cookie=0, duration_sec=0s, duration_nsec=881000000s, table_id=1, priority=32768, n_packets=0, n_bytes=0, idle_timeout=60,hard_timeout=0,in_port=1,actions=output:2
