6)  ------------ Retransmit Message from step 2 -------------
      Length + Non-ESP Marker  ------->
      INFORMATIONAL
      HDR, SK { N(UPDATE_SA_ADDRESSES),
      N(NAT_DETECTION_SOURCE_IP),
      N(NAT_DETECTION_DESTINATION_IP) }
                               <------- Length + Non-ESP Marker
                                                  INFORMATIONAL
                          HDR, SK { N(NAT_DETECTION_SOURCE_IP),
                              N(NAT_DETECTION_DESTINATION_IP) }
  7)  -- New Exchange with recalculated  NAT_DETECTION_*_IP ---
      Length + Non-ESP Marker  ------->
      INFORMATIONAL
      HDR, SK { N(UPDATE_SA_ADDRESSES),
      N(NAT_DETECTION_SOURCE_IP),
      N(NAT_DETECTION_DESTINATION_IP) }
                               <------- Length + Non-ESP Marker
                                                  INFORMATIONAL
                          HDR, SK { N(NAT_DETECTION_SOURCE_IP),
                              N(NAT_DETECTION_DESTINATION_IP) }
  8)  <---------------------> IKE/ESP Flow <------------------>