An OF controller can program forward action, when a specific flow is to be forwarded using regular router forwarding. This would be a default behavior if the filter-policy embedding this OF switch instance has a default-action forward and no filter policy rule matches the flow. To implement forward action, the following OF encoding is used:
flow_mod:
instruction type: OFPIT_WRITE_ACTIONS or OFPIT_APPLY_ACTION,
action type: OFPAT_OUTPUT,
port= NORMAL
where NORMAL is an OF reserved value.