LINK_ERR Occurs Due to an Optical Module Fault on the TQX Board

This section describes how to remove the LINK_ERR alarm resulting from an optical module fault on the TQX board.

Product

OptiX OSN 8800

Fault Type

Tributary Unit and Line Unit

LINK_ERR

Symptom

There are two channels of point-to-point 10G LAN services between station A and station B in a network. The TQX tributary board and NQ2 line board are used at either station. After the network connects to a router, it is found that both station A and station B report the LINK_ERR alarms in one channel of 10G LAN services. As a result, this channel of 10G LAN services is interrupted. However, the other channel of 10G LAN service runs normally.

Cause Analysis

The possible causes of this problem are as follows:

• The working mode of receive optical interface on WDM side the NQ2 board at the local station is different from the working mode of the transmit optical interface on the WDM side of the NQ2 board at the opposite station.
• The link is faulty.
• Optical fiber connections are incorrect.
• The opposite equipment is faulty.
• The input optical power of the client-side optical interface on the TQX board is excessively high or low.
• The working modes of the optical interfaces on the client side of the TQX board are inconsistent.
• The board at the local station is faulty.

Procedure

1. Exclude the possibility that working modes of the optical interfaces on the client side of the TQX board are inconsistent since the TQX board has no PHY chip.
2. Check the client-side optical power on the TQX board, finding that the receive optical power on the client side of the TQX board at station A is -6.7 dBm and that at station B is -8.1 dBm. Both of the receive optical power values are in normal range.
3. Make sure that the chip for detecting link status information is located behind the cross-connect chip since the TQX board has no Layer 2 chip. Then, configure an inloop on the client side of the NQ2 board at each of station A and station B, finding that the LINK_ERR alarm on the TQX board at station A is cleared but the LINK_ERR alarm on the TQX board at station B persists.
4. Perform a cold reset on the TQX board at station B. The LINK_ERR alarm persists.
5. Replace the optical module at optical interface 3 on the client side of the TQX board at station B, finding that the LINK_ERR alarm is cleared.
6. Release the inloop at stations A and B. At this point, the LINK_ERR alarm is cleared and normal connection between the network and the router is achieved.

Result

The problem is resolved.

Reference Information

None.

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