Configuring the T1 Remote Loopback Response
The T1 facilities data-link loop request signal is used to communicate various network information in the form of in-service monitoring and diagnostics. Extended superframe, through the facilities data link (FDL), supports nonintrusive signaling and control, thereby offering clear-channel communication. Remote loopback requests can be over the FDL or inband. To configure the router to respond to remote loopback requests, include the remote-loopback-respond statement at the [edit interfaces interface-name t1-options] hierarchy level:
By default, the router does not respond to remote loopback requests.