Defines if a F4 segment OAM cell is transmitted due to problems in the other port, i.e. physical layer alarm or F4 defect. This is valid only when the ACE101 has ATM UNI interfaces in both sides and is configured for 'Non-Intrusive' mode. none - AIS is not sent to any of the ports. user - F4 AIS will be sent toward the user when defect is detected in the network port. network - F4 AIS will be sent toward the network when defect is detected in the user port. both - F4 AIS will be sent toward the network when defect is detected in the user port and toward the user when defect is detected in the network port.