[ovs-discuss] system at dp0: execute 0, 1 failed (Invalid argument) on packet

Rob Sherwood rob.sherwood at bigswitch.com
Fri Sep 2 08:45:11 PDT 2011

On Fri, Sep 2, 2011 at 8:24 AM, Ben Pfaff <blp at nicira.com> wrote:
> The in_port is also important when the packet_out's actions include an
> output to OFPP_FLOOD.

[Apologies if I'm being pedantic, but some of this is a little subtle.]

Fwiw, the in_port is actually used as a parameter to all output port
actions.  In openflow, there is an explicit rule that the output port
cannot be the same as the input port, to prevent flooding (if you
really want to send out the input port, you can use OFPP_IN_PORT).
Also, as Ben mentioned, OFPP_FLOOD and OFPP_ALL both mean "except the
input port".  So, this is why there is an in_port parameter for both
ofp_packet_out and ofp_flow_mod.  If the packet is not coming from a
physical port, e.g., if it's coming from the controller, the right
thing to do is to set the inport to OFPP_NONE.

- Rob

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