If no intra-board cross-connection from the WDM side to the client side is configured for boards that
support intra-board cross-connections, these boards may falsely report TD alarms when their optical
port lasers are turned on.
The problem occurs on a board when the following conditions are present:
The board is listed in the table above. No intra-board cross-connection shown in Figure 1 is configured
on the board. Specifically, no unidirectional cross-connection from the WDM side to the client side is
configured on the board.
Figure 1 Intra-board cross-connection
Pluggable optical modules are used on the board and the optical port lasers are turned on.
TD alarms are reported.
The problem occurs if the trigger conditions and symptom are satisfied.
When no intra-board cross-connection shown in Figure 1 is configured on the board, the module bias
current increases. In addition, the laser transmit efficiency decreases when the ambient temperature
increases. To maintain stable module power, the bias current further increases. When the bias current
increases to a value greater than the alarm threshold, TD alarms are reported. The laser transmit efficiency
varies according to modules. Therefore, not all modules have this problem.
The board falsely reports TD alarms. Consequently, operators may consider that the optical modules are faulty.
Take either of the following measures:
Turn off the lasers after confirming that no service is deployed.
Configure intra-board cross-connections for the related optical ports.
Turn on the lasers after configuring intra-board cross-connections.
Update the related product manuals. Specifically, add descriptions in the product manuals that intra-board
cross-connections shown in Figure 1 must be configured for the boards listed in the table above if the lasers
on these boards are turned on to test light emitting.