Wednesday, September 28, 2016

LASER_MODE_ERR Caused by the Incorrect Optical Module on the SL16 Board

The LASER_MODE_ERR alarm occurs because an incorrect optical module is used on the SL16 board. This problem is solved by replacing the incorrect optical module with a correct one.

Fault Type

LASER_MODE_ERR

Symptom

The SL16 board on the OptiX OSN 3500 reports the LASER_MODE_ERR alarm. The SL16 board is interconnected with a 2.5 Gbit/s optical interface and does not report any abnormal alarm about optical signals.

Cause Analysis

Query the board manufacturing information.

shows the query result.
The query result indicates that the optical module on the SL16 board is MXPD-243S and has a rate of 622 Mbit/s. In fact, the optical module is a GE module.
The board reports the LASER_MODE_ERR alarm because the rate of the optical module (1.25 Gbit/s) is different from the rate of the board (2.5 Gbit/s). When you query the SDH signal rate of the optical module, the maximum rate of the optical module is the maximum rate lower than 1.25 Gbit/s. Therefore, the query result indicates that the maximum rate of the optical module is 622 Mbit/s.

Procedure

  1. Replace the original optical module with a 2.5 Gbit/s optical module. The SL16 board receives and transmits STM-16 signals, so the 2.5 Gbit/s optical module matches the board. Then, the LASER_MODE_ERR alarm clears.

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