H3C SR6600 Configuration Manual page 55

Solution
The symptom might occur when the router and its directly connected SDH device have different
multiplex paths for the E1 channels. Multiplex path inconsistency can cause PPP negotiation failure
because the SDH device transmits signals from the router in incorrect timeslots to the remote end. If
the SDH device incorrectly maps a signal to an idle timeslot in a looped condition, the router can
detect a loop on the serial interface.
To resolve the problem:
1. Identify the multiplex path for the E1 channels on the router.
<H3C> display controller cpos e1
2. Verify that the router and its directly connected SDH device have the same multiplex path for E1
channels. (Details not shown.)
3. Debug the loop condition.
<H3C> debugging ppp lcp error
4. If the problem persists, contact H3C Support.
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