serial port spontaneously goes into looped mode

[ntaylor]

Cisco 1601 router with integrated csu/dsu spontaneously places the serial1 port into looped mode, if I reload the interface status is up and up, at various intervals of time the interface will show up and up (looped) ,the loop led on the csu/dsu is lighted at this time. contacted telco and they are not doing anything to initiate this state, to change the state (temporarily) I can either reload or toggle the loopback switch on the csu/dsu

[b.scherer]

when you see the loop on your ce what does the telco see? if telco see's a loop unplug your equipment and leave the t1 open ended and ask the tech what he see's. i wouldn't rule out the carrier yet. you can try no loop rem/no loop dte/no loop lin under the interface to try and get rid of the loop temporarily. if you have some spare equipment make a t1 cable and directly connect your router to another router with a t1 card and see if it goes into loop.