When the controller wants to delete a flow table entry, it sends a flow entry modification message (OFPT_FLOW_MOD) to the switch, with the command value set as OFPFC_DELETE / OFPFC_DELETE_STRICT. This flow table modification message contains the information required to identify and delete the entry from the flow table.
The message format that will be used by the controller to send the OFPT_FLOW_MOD message is defined in the Adding a new flow entry to the flow table recipe in Chapter3, Flow Table and Flow Entry Modification Messages (Part 2). The OpenFlow specification defines two different variants for deleting the flow entry as strict and non-strict versions.
When the switch receives the OFPT_FLOW_MOD message with the command field set as OFPFC_DELETE_STRICT, all the fields in the flow modification message should be matched strictly against the flow table entry, and should be deleted from the flow table.
When the switch receives the OFPT_FLOW_MOD...