Product |
Top Assembly |
Printed Circuit Assembly |
Comments |
||
---|---|---|---|---|---|
Part Number |
Rev. |
Part Number |
Rev. |
||
15454E-L64.2-1-HS= |
800-21799-01 800-21799-01 |
All |
73-6783-01 73-6783-01 |
All |
Failure possible in environments exceeding 50°C/122°F |
15454-OC192LR1550= |
800-07014-01 |
All |
73-5519-01 |
All |
Failure possible in environments exceeding 50°C/122°F |
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.
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.
Traffic Loss or Equipment Interconnect Failure ALARM in CTC.
There is no workaround.
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:
Product Alert Tool - Set up a profile to receive email updates about reliability, safety, network security, and end-of-sale issues for the Cisco products you specify.