How to handle invalid TTL packets with flow mods? RYU OpenFlow 1.3

Question

I want to forward packets with invalid TTL to the controller. Is there any way to set a flow mod for that?

Answer 1

The answer is yes, you can do it. Accoring to this Ryu controller doc page , you can get packets with invalid TTL in packet_in_handler function of your sdn application:

@set_ev_cls(ofp_event.EventOFPPacketIn, MAIN_DISPATCHER)
def packet_in_handler(self, ev):
    msg = ev.msg
    dp = msg.datapath
    ofp = dp.ofproto

    if msg.reason == ofp.OFPR_NO_MATCH:
        reason = 'NO MATCH'
    elif msg.reason == ofp.OFPR_ACTION:
        reason = 'ACTION'
    elif msg.reason == ofp.OFPR_INVALID_TTL:
        reason = 'INVALID TTL'
    else:
        reason = 'unknown'

    self.logger.debug('OFPPacketIn received: '
                      'buffer_id=%x total_len=%d reason=%s '
                      'table_id=%d cookie=%d match=%s data=%s',
                      msg.buffer_id, msg.total_len, reason,
                      msg.table_id, msg.cookie, msg.match,
                      utils.hex_array(msg.data))

For more information about OpenFlow, Packet_in message read OpenFlow specification 1.3 .