Summary:In versions from OptiX OSN 8800/6800 V100R006C00 to OptiX OSN 8800/6800 V100R008C00, if network cables of the master subrack and slave subrack on an NE are connected as a ring and the subrack cascading mode is set to Ring, there is a possibility that the NE becomes unreachable during the activation process of an upgraded to a version earlier than OptiX OSN 8800/6800 V100R006C10. This triggers an automatic rollback during the upgrade.
Product Model: OptiX OSN 8800 OptiX OSN 6800
Keywords: subrack cascading, ring, tree, unreachable, rollback
[Problem Description]
Trigger conditions:
The problem is triggered when all the following conditions are met:
The device type is OptiX OSN 8800 or OptiX OSN 6800.
The source version for the upgrade is any version from V100R006C00 to V100R008C00.
The network cables of the master subrack and slave subrack on the NE are connected as a ring, and the subrack cascading mode is set to Ring.
The upgrade is in package loading mode and the target version is earlier than V100R006C10.
Symptom:
During NE activation, the NE becomes unreachable and cannot be restored.
A rollback is automatically performed on the NE during the upgrade.
Identification method:
On the NMS, verify that the type of the NE unreachable is OptiX OSN 8800 or OptiX OSN 6800.
In the upgrade task management window, verify that the source version for the upgrade is any version from V100R006C00 to V100R008C00 and the target version is earlier than V100R008C10.
Verify onsite that the network cables of the master subrack and slave subrack are connected as a ring. Connect to the NE using a PC. On the maintenance terminal, verify that the subrack cascading mode is set to Ring.
Note: In areas that have high security requirements, use the cmdclient command.
[Root Cause]
In versions from OptiX OSN 8800/6800 V100R006C00 to OptiX OSN 8800/6800 V100R008C00, the ring where the subracks of the NE are located has defects. These cause a network storm. As a result:
There is a possibility of a failure to receive ring detection frames. The ring opening function becomes invalid and the subracks go offline, causing an activation failure and triggering a version rollback.
The CPU of the SCC board on the master subrack is busy, causing the NE unreachable.
The involved boards include TN11AUX, TN12AUX, TN15AUX, TN16AUX, TN18EFI, TN41AUX, TN51AUX, and TN52AUX.
[Impact and Risk]
The NE becomes unreachable during activation, and the NE automatically rolls back upon an activation
failure.
[Measures and Solutions]
Recovery measures:
Connect to the NE using a PC onsite, change the subrack cascading mode to Tree, change the ring network to a chain network, and upgrade the NE.
The following are examples of the commands for changing and querying the subrack cascading mode:
Command for changing the subrack cascading mode:
Note: In areas that have high security requirements, use the cmdclient command.
Workarounds:
See "Recovery measures" as described previously.
Perform a health check before the upgrade. For V100R007C00 and later versions, the health check script contains the item Check whether subrack ring protection is configured on NEs. If the message "The subrack connection mode is Ring" is displayed during the health check, perform the operations described in "Recovery measures."
Solution:
Upgrade the live-network NEs to OptiX OSN 8800/6800 V100R008C10 or a later version.
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