Flow_mod_event

The flow mod event is triggered when a call is made to the NOX API to add or modify a flow. For example, it's triggered by a successful call to install_datapath_flow().

Note that a flow mod event is triggered when the method is successful and is not confirmation from the switch that it was added. When sending an ofp_flow_mod request (see OpenFlow protocol), if the OFPFF_CHECK_OVERLAP flag is set, then duplicate flows cannot be added. Adding a duplicate flow will trigger a flow mod event, but it will also trigger an error event since the flow could not actually be added.