Cisco ONS 15400 Series

Revised March 26, 2004

September 3, 2003

Products Affected

Problem Description

On both 15454E-L64.2-1-HS and 15454-OC192LR1550 cards, the backplane phase-locked loop (PLL) phase detector operates in the range of 0.8 volts (V) to 1.35 V. The optimum operating point is in the center of the range, or 1.075 V. On the affected cards, the operating point is set to 1.22 V.

The temperature compensation circuit on this board moves this point upward as the temperature rises. It can reach 1.3 V at 50 degrees Celsius, 122 degrees Fahrenheit, so there is little margin in this design.

The failure mode is a total loss of traffic on the backplane due to the unlocked backplane PLL. Software repeatedly tries to lock up the PLL and, in many instances, succeeds after some time, in seconds.

Sometimes, software is not able to achieve lock, even after repeated tries. In either case, an alarm is displayed on the Cisco Transport Controller (CTC) screen against the failing OC192 card: Interconnection Equipment Failure - Working or Interconnection Equipment Failure - Protect.

Background

At high temperature, exceeding 50 degrees Celsius or 122 degrees Fahrenheit, the backplane PLL can suddenly go out of lock with loss of traffic and not be able to recover gracefully. The instance of this failure mode is extremely low.

Problem Symptoms

Traffic Loss or Equipment Interconnect Failure ALARM in CTC.

Workaround/Solution

There is no workaround.

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:

• Open a service request on Cisco.com
• By email
• By telephone

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