NE80E is connected with multi-mode tail fiber of NE40E. After a while, the LED of NE80E is normal. However, the interface of NE40E is Down. The current connection is interrupted.
The LED of NE40E is off.
%Jun 14 11:15:47 2007 ngn-r4-a-ahhf-2 PHY/2/PHY:Slot=7; GigabitEthernet7/0/1: change status to down
1. Check NE40E and the interface is not shutdown and has no loopback.
2. Shut down the interface of NE40E. The interface of NE80E is also Down. The connected tail fiber is normal.
3. The optical power cannot be measured. Change the receiving and sending tail fibers of both ends. As a result, NE80E is normal and NE40E is still Down.
4. Change the optical module of NE40E to other interfaces. The problem persists. The connection of the board and backplane is normal.
5. To locate which optical module is abnormal, after the optical modules of NE80E and NE40E are changed, the interface of NE80E is Down. The receiving of NE40E is normal and the link is Up. The sending of the optical module of NE80E is abnormal.
6. Change the optical module of NE80E. Then the links at both ends are normal.
The optical channel of NE80E shows that NE80E receives the light from NE40E only, while the interface of NE40E is Down. The receiving of the optical module is abnormal or the tail fiber fails.
If there is no optical power meter or the type of the interface is incorrect, change optical modules of both ends to locate the problem.