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How to Capture the OpenFlow Messages?

capture-the-openflow-messages

Step by Step Capture the OpenFlow Messages

  • Description:
    OpenFlow is a protocol that allows a server to tell network switches where to transmit packets. OpenFlow messages manipulated the flow entries in the flow table where messages are interchanged between the switch and controller via a secure channel. By maintaining a flow table, the switch can make forwarding decisions for incoming packets using a simple look at the entries of its flow table. The OpenFlow Protocol supports three message types, each with its own sub-types setup: 1. Controller-to-switch 2. Asynchronous, and 3. Symmetric. The Controller-to-switch Messages include Features, Configuration, Modify-State, Read-States, Packet Outs, Barrier, Role-Request, and Asynchronous-Configuration. The Asynchronous messages include Packet-in, Flow-Removed, Port Status, and Error. The Symmetric messages include Hello, Echo and Experimenter. To capture the OpenFlow messages, users have to follow the samples discussed in the below section:
Open 4 Terminals:

    In Terminal1,

  • sudo wireshark
    capture-the-openflow-messages-1
  • And start the capture for "loopback" or "any" interface
    capture-the-openflow-messages-2

  • In Terminal2,

  • ryu-manager ryu.app.simple_switch_13
    capture-the-openflow-messages-3

  • In Terminal3,

  • Sudomn --controller=remote,ip=127.0.0.1 --mac --switch=ovsk,protocols=OpenFlow13 --topo=single,4
    capture-the-openflow-messages-4
  • You will get the mininet prompt.
  • In the mininet prompt, type pingall command
  • pingall
    capture-the-openflow-messages-5

  • In Terminal4,

  • sudo ovs-vsctl show
    capture-the-openflow-messages-6
  • sudo ovs-ofctl -O OpenFlow13 dump-flows s1
    capture-the-openflow-messages-7
  • Check the OpenFlow messages in Wireshark,
  • Stop the Wireshark capture,
  • In the filter, type "openflow_v4" to see the OpenFlow Messages.
  • capture-the-openflow-messages-8