Cisco ONS 15300 Series

Field Notice: FN#62097- ONS15454 and ONS15327, R4.6.1 and Later PDI-P Insertion to Non-Conforming Equipment Can Cause Outages During or After Software Upgrades

June 02, 2005

Products Affected

  • 15327 - CISCO15327

  • 15454 - CISCO15454

  • 15454-R4.6.1SWCD - R4.6.1 and later

Problem Description

Equipment that does not read C2 bytes, in accordance with GR-253 Section does not interoperate properly with the ONS15454 and ONS15327. Cisco procedures take steps to avoid undesirable outcomes caused by this interoperability issue, but when those procedures are not followed traffic outages can result. When using Release 4.6.1 and later software and the default value of ENABLE for PDI-P generation:

  • If there is any VT defect, the entire STS with the defective VT will go down.

  • Creating a new VT circuit with a defect will cause the entire STS that has that VT to go down until the VT circuit is repaired.


In software version 4.6.1 or later, there is a feature called PDI-P generation. This feature is based on GR-253 specifications. It monitors VT defects and tallies a total count. The total count is converted to the corresponding C2 byte value. The new C2 byte is sent to the downstream node. Legacy equipment from some vendors does not recognize these C2 byte values and drops traffic. In Release 4.6.1 and later, the default for PDI-P generation is set to ENABLE. Upon upgrade, if any defects are detected, any non-conforming legacy equipment will immediately detect the problem and drop all VTs within the STS.

The PDI-P defaults for recent releases are set as follows:

  1. Upgrades from pre-4.61 to pre-5.05 will set the PDI-P generator to ENABLE by default.

  2. Upgrades from pre-4.61 to 5.05 and later will set the PDI-P generator to DISABLE by default.

  3. An upgrade from 4.61 or later will always maintain the provisioned value.

Problem Symptoms

Loss of all VTs in the STS circuit that carried VTs with alarms raised before the sw upgrade.


  1. Eliminate all VT defects (alarms) before upgrading the software. This can be done by the following:

    • Delete any circuits that are no longer needed.

    • Change the circuits state to OOS if this circuit is waiting to be turned up.

    • For circuits that are in service, repair the defect.

  2. After the software upgrade, disable the PDI-P generation and restore any circuits to IS.

For More Information

If you require further assistance, or if you have any further questions regarding this field notice, please contact the Cisco Systems Technical Assistance Center (TAC) by one of the following methods:

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