Hi Rafael, When the switch receives a packet, it first checks with its flow tables if there is a flow entry matching that packet's headers. The fields that the switch tries to match are Src IP, Dest IP, Src MAC, Dest MAC, VLAN tag etc. (you can get a full list in the openflow spec sheet) If there is a matching entry, the switch performs the action mentioned in the flow entry. (each flow entry is made up of "matching fields", "flow action" and "statistics").
If there is no matching entry, the switch does not send the whole packet to the controller, the switch stores the packet in a buffer. It sends a "packet_in" openflow message to the controller. This message contains all the header fields that the controller will need to check with it's own database. The controller does not need the payload to dictate a decision to the switch. hence, the switch only sends the header fields. The controller then checks with the applications running on it whether they have defined any flow for that particular packet's header field instances. If yes, it sends another openflow message to the switch dictating the flow entry to be added for all packets with that particular header field instance. The switch receives this message, installs a flow entry and performs the action mentioned in the 'action' part of the entry it just created. Hope this helps. I'm relatively new to openflow. It'l be awesome if someone could confirm what I've written. Naman On Fri, Dec 7, 2012 at 5:13 AM, Rafael Gomes <[email protected]> wrote: > > > Good morning, > > I have a simples questions about openflow, because i'm a little confuse... > > > When we have a network with OpenFlow protocol worked with openvswitch and > floodlight controller. My question is about, what happens when arrive a > packets a switch. The switch look for your flow table and no matched, then > he should send packet to the controller. > what does the controller in this moment with de packet? > > > Thanks for your help > > Best regards. > > Rafael Gouveia. > > _______________________________________________ > openflow-discuss mailing list > [email protected] > https://mailman.stanford.edu/mailman/listinfo/openflow-discuss > >
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