how to check / find out the root cause of Link down on SFP Fiber Link

[Paul11]

How to check / find out the root cause of Link down on SFP Fiber Link

Fiber cable error ? SFP module error ? Why was the Link down?

The link is sharing port. LACP L2 (1:21 and 2:21)
Now the link is up and running.
I didn't see any collisions/congestion/anomalyrxerrors/txerrors on the port

Link State: Active, 1Gbps, full-duplex and AUTO

following is the log

09/25/2015 11:31:22.76 Slot-1: Add port 1:21 to aggregator09/25/2015 11:31:22.72 Slot-1: Port 1:21 link UP at speed 1 Gbps and full-duplex
09/25/2015 11:31:22.15 Slot-1: Remove port 1:21 from aggregator
09/25/2015 11:31:22.14 Slot-1: Port 1:21 is Down, remove from aggregator 1:21
09/25/2015 11:31:22.14 Slot-1: Port 1:21 link down

Appreciate your help.

Regards,
Paul

[Paul11]

Please advice any info to find out root cause. thanks.

[Marco_Lorenz]

I had exactly the same error with flapping links and it was fixed by TAC with the above command.

[Marco_Lorenz]

Conf Port 1:21,2:21 debounce timer 150

[OscarK]

Hello Paul,

that is not so good, not much we can see then other that the SFP notifies us the link goes down.

best regards

[Paul11]

Hi OscarK,

transceiver is not support.

sw# show ports 2:24 transceiver information detail
Port : 2:24
Error: DDMI is not supported on this LX transceiver

----------------------------------------------

Slot-1 sw01.1 # debug hal show optic-info slot 1
Port 21
SFP or SFP+: SFP
Signal: present
TX Fault: no
SFP/SFP+ Vendor: OPNEXT INC
SFP/SFP+ Part Number: TRF5735AALB206
SFP/SFP+ Serial Number: C09B08646
SFP/SFP+ Manufacture Date: 090214
SFP/SFP+ Type: SFP
Connector: LC
GE Compliance: 1000BASE-LX
Wavelength: 1310