Description: Determines whether loopback is enabled and what kind of loopback is enabled.

Options: n/a (0): object is not applicable

none (1): Loopback is not enabled

local (2): Local loopback is enabled (return outbound frames to the originating software layer without transmitting them)

remote (3): Remote loopback is enabled (forces the port to return (transmit) any frame received on the line, and causes the port to deny communication with any upper layer that requests service)

both (4):Both local and remote loopbacks are enabled.

isdn-uif-uif (5): ISDN loopback is enabled at U-Interface (forces TB1Q signal from a remote transmitter to pass through the entire U-Interface Transceiver before being transmitted back to the remote receiver)

isdn-uif-idl2 (6): ISDN loopback is enabled at IDL2 Controller (forces IDL2 Controller to take in B and D channel data on IDL RX pin and send it out on IDL2 TX pin)

isdn-uif-framer (7): ISDN loopback is enabled at framer (forces B and D channel data in on D-in pin and M channel data in on SCP which together undergo framing and deframing functions before B and D channel data go out D-out pin and M channel data go out SCP)

isdn-uif-external (8): ISDN loopback is enabled at external line (forces TB1Q signal coming in on D-in pin to pass through Tx Driver pins, the U-Interface circuit and Rx input pins before recovering it and sending it out the D-out pin)

Default Value: none