dpctl 程序是一个命令行工具用来检测和管理 OpenFlow 数据通路，它能够显示当前的状态数据通路，包括功能配置和表中的条目，以及合适使用 OpenFlow 的内核模块，可以用来添加，删除，修改和监视 datapaths。
TCP 端口 6634 是默认交换机监听端口。
# dpctl show tcp:9.123.137.25:6634
features_reply (xid=0x94af8117): ver:0x1, dpid:1
n_tables:255, n_buffers:256
features: capabilities:0xc7, actions:0xfff
1(s1-eth1): addr:2e:d1:ca:aa:af:67, config: 0, state:0
current: 10GB-FD COPPER
2(s1-eth2): addr:66:93:32:1e:9b:9e, config: 0, state:0
current: 10GB-FD COPPER
LOCAL(s1): addr:5e:bc:ab:cc:dc:43, config: 0x1, state:0x1
get_config_reply (xid=0x92fc9e48): miss_send_len=0
此时，流表为空，执行 h1 ping h2 无法得到响应。需要手动添加流表项，实现转发。
# dpctl dump-flows tcp:9.123.137.25:6634 stats_reply (xid=0xe2c7ea1e): flags=none type=1(flow)
此时查看流表可以看到新的转发信息，同时可以在 h1 和 h2 之间可以相互连通。
# dpctl add-flow tcp:9.123.137.25:6634 in_port=1,actions=output:2 # dpctl add-flow tcp:9.123.137.25:6634 in_port=2,actions=output:1 # dpctl dump-flows tcp:9.123.137.25:6634 stats_reply (xid=0x131ed782): flags=none type=1(flow) cookie=0, duration_sec=13s, duration_nsec=401000000s, table_id=0, priority=32768, \ n_packets=0, n_bytes=0,idle_timeout=60,hard_timeout=0,in_port=1,actions=output:2 cookie=0, duration_sec=5s, duration_nsec=908000000s, table_id=0, priority=32768, \ n_packets=0, n_bytes=0,idle_timeout=60,hard_timeout=0,in_port=2,actions=output:1
#dpctl adddp n1:0
#dpctl adddp n1:0 eth0 #dpctl adddp n1:0 eth1
#dpctl monitor n1:0
#dpctl delif nl:0 eth0
建立一台openflow交换机、连接三台交互机，没有连接控制器的虚拟网络，可以看到h1和h2是不通的。
$ sudo mn --topo single,3 --mac --switch ovsk --controller remote *** Creating network *** Adding controller Unable to contact the remote controller at 127.0.0.1:6653 Unable to contact the remote controller at 127.0.0.1:6633 Setting remote controller to 127.0.0.1:6653 *** Adding hosts: h1 h2 h3 *** Adding switches: s1 *** Adding links: (h1, s1) (h2, s1) (h3, s1) *** Configuring hosts h1 h2 h3 *** Starting controller c0 *** Starting 1 switches s1 ... *** Starting CLI: mininet> dpctl dump-flows *** s1 ------------------------------------------------------------------------ NXST_FLOW reply (xid=0x4): mininet> dump <Host h1: h1-eth0:10.0.0.1 pid=24213> <Host h2: h2-eth0:10.0.0.2 pid=24215> <Host h3: h3-eth0:10.0.0.3 pid=24217> <OVSSwitch s1: lo:127.0.0.1,s1-eth1:None,s1-eth2:None,s1-eth3:None pid=24222> <RemoteController c0: 127.0.0.1:6653 pid=24205> mininet> link invalid number of args: link end1 end2 [up down] mininet> links h1-eth0<->s1-eth1 (OK OK) h2-eth0<->s1-eth2 (OK OK) h3-eth0<->s1-eth3 (OK OK) mininet> h1 ping -c 2 h3 PING 10.0.0.3 (10.0.0.3) 56(84) bytes of data. From 10.0.0.1 icmp_seq=1 Destination Host Unreachable From 10.0.0.1 icmp_seq=2 Destination Host Unreachable
$ sudo ovs-vsctl show
2b05a0c0-015b-44cd-8ce8-d540d9f551c4
Bridge "s1"
Controller "tcp:127.0.0.1:6653"
Controller "ptcp:6654"
fail_mode: secure
Port "s1-eth2"
Interface "s1-eth2"
Port "s1-eth1"
Interface "s1-eth1"
Port "s1-eth3"
Interface "s1-eth3"
Port "s1"
Interface "s1"
type: internal
ovs_version: "2.5.2"可看出是6654。
~$ dpctl add-flow tcp:127.0.0.1:6654 in_port=1,actions=output:2 ~$ dpctl add-flow tcp:127.0.0.1:6654 in_port=2,actions=output:1 ~$ dpctl dump-flows tcp:127.0.0.1:6654 stats_reply (xid=0xbf1d157c): flags=none type=1(flow) cookie=0, duration_sec=18s, duration_nsec=579000000s, table_id=0, priority=32768, n_packets=0, n_bytes=0, idle_timeout=60,hard_timeout=0,in_port=1,actions=output:2 cookie=0, duration_sec=12s, duration_nsec=103000000s, table_id=0, priority=32768, n_packets=0, n_bytes=0, idle_timeout=60,hard_timeout=0,in_port=2,actions=output:1
建立s1端口1和2的双向转发。在mininet里。s1-eth1和s1-eth2的转发流表已经建立了，故h1和h2能ping通，而h1和h3不行。
mininet> dpctl dump-flows *** s1 ------------------------------------------------------------------------ NXST_FLOW reply (xid=0x4): cookie=0x0, duration=13.858s, table=0, n_packets=0, n_bytes=0, idle_timeout=60, idle_age=13, in_port=2 actions=output:1 cookie=0x0, duration=6.319s, table=0, n_packets=0, n_bytes=0, idle_timeout=60, idle_age=6, in_port=1 actions=output:2 mininet> h1 ping -c 2 h2 PING 10.0.0.2 (10.0.0.2) 56(84) bytes of data. 64 bytes from 10.0.0.2: icmp_seq=1 ttl=64 time=0.338 ms 64 bytes from 10.0.0.2: icmp_seq=2 ttl=64 time=0.072 ms --- 10.0.0.2 ping statistics --- 2 packets transmitted, 2 received, 0% packet loss, time 1023ms rtt min/avg/max/mdev = 0.072/0.205/0.338/0.133 ms mininet> h1 ping -c 2 h3 PING 10.0.0.3 (10.0.0.3) 56(84) bytes of data. From 10.0.0.1 icmp_seq=1 Destination Host Unreachable --- 10.0.0.3 ping statistics --- 2 packets transmitted, 0 received, +1 errors, 100% packet loss, time 1015ms
这时h1和h2又不通了。
~$ dpctl del-flows tcp:127.0.0.1:6654
sh ovs-ofctl add-flow s1 action=normal
将交换机s1的转发行为设置为normal，流表将会自动更新。
sh ovs-ofctl del-flows s1
以下演示自定义在不同网络层之间的流匹配。
sh ovs-ofctl add-flow s1 priority=500, in_port=1, actions=output:2 sh ovs-ofctl add-flow s1 priority=500, in_port=2, actions=output:1
sh ovs-ofctl add-flow s1 dl_src=00:00:00:00:00:01, dl_dst=00:00:00:00:00:02, actions=output:2 sh ovs-ofctl add-flow s1 dl_src=00:00:00:00:00:02, dl_dst=00:00:00:00:00:01, actions=output:1 sh ovs-ofctl add-flow s1 dl_type=0x806,nw_proto=1,actions=flood
sh ovs-ofctl add-flow s1 priority=500, dl_type=0x800, nw_src=10.0.0.0/24, nw_dst=10.0.0.0/24, actions=normal sh ovs-ofctl add-flow s1 priority=800, ip,nw_src=10.0.0.3,actions=mod_nw_tos:184,normal sh ovs-ofctl add-flow s1 arp,nw_dst=10.0.0.1,actions=output:1 sh ovs-ofctl add-flow s1 arp,nw_dst=10.0.0.2,actions=output:2 sh ovs-ofctl add-flow s1 arp,nw_dst=10.0.0.3,actions=output:3
h3 python -m SimpleHTTPServer 80 & sh ovs-ofctl add-flow s1 arp,actions=normal sh ovs-ofctl add-flow s1 priority=500,dl_type=0x800,nw_proto=6,tp_dst=80,actions=output:3 sh ovs-ofctl add-flow s1 priority=800,ip,nw_src=10.0.0.3,actions=normal h1 curl h3 h2 curl h3