Field Notice: ONS 15252/15201 Long Range CLIPs Can Generate Bit Errors at Low Temperatures

Updated January 7, 2002

October 10, 2001

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Products Affected

Product	Top Assembly		Printed Circuit Assembly		Comments
	Part Number	Rev.	Part Number	Rev.
CH23/L/P/SC/15200=	800-13419-01	G0	73-5875-04	A0	PROTECTED
CH25/L/P/SC/15200=	800-13420-01	F0	73-5875-04	A0	?
CH27/L/P/SC/15200=	800-13421-01	F0	73-5875-04	A0	?
CH29/L/P/SC/15200=	800-13422-01	F0	73-5875-04	A0	?
CH31/L/P/SC/15200=	800-13423-01	F0	73-5875-04	A0	?
CH33/L/P/SC/15200=	800-13424-01	F0	73-5875-04	A0	?
CH35/L/P/SC/15200=	800-13425-01	F0	73-5875-04	A0	?
CH37/L/P/SC/15200=	800-13426-01	F0	73-5875-04	A0	?
CH43/L/P/SC/15200=	800-13427-01	F0	73-5875-04	A0	?
CH45/L/P/SC/15200=	800-13428-01	F0	73-5875-04	A0	?
CH47/L/P/SC/15200=	800-13429-01	F0	73-5875-04	A0	?
CH49/L/P/SC/15200=	800-13430-01	F0	73-5875-04	A0	?
CH51/L/P/SC/15200=	800-13431-01	F0	73-5875-04	A0	?
CH53/L/P/SC/15200=	800-13432-01	F0	73-5875-04	A0	?
CH55/L/P/SC/15200=	800-13433-01	F0	73-5875-04	A0	?
CH57/L/P/SC/15200=	800-13434-01	F0	73-5875-04	A0	?
CH23/L/U/SC/15200=	800-13450-01	G0	73-5875-04	A0	UNPROTECTED
CH25/L/U/SC/15200=	800-13451-01	F0	73-5875-04	A0	?
CH27/L/U/SC/15200=	800-13452-01	F0	73-5875-04	A0	?
CH29/L/U/SC/15200=	800-13453-01	F0	73-5875-04	A0	?
CH31/L/U/SC/15200=	800-13454-01	F0	73-5875-04	A0	?
CH33/L/U/SC/15200=	800-13455-01	F0	73-5875-04	A0	?
CH35/L/U/SC/15200=	800-13456-01	F0	73-5875-04	A0	?
CH37/L/U/SC/15200=	800-13457-01	F0	73-5875-04	A0	?
CH43/L/U/SC/15200=	800-13458-01	F0	73-5875-04	A0	?
CH45/L/U/SC/15200=	800-13459-01	F0	73-5875-04	A0	?
CH47/L/U/SC/15200=	800-13460-01	F0	73-5875-04	A0	?
CH49/L/U/SC/15200=	800-13461-01	F0	73-5875-04	A0	?
CH51/L/U/SC/15200=	800-13462-01	F0	73-5875-04	A0	?
CH53/L/U/SC/15200=	800-13463-01	F0	73-5875-04	A0	?
CH55/L/U/SC/15200=	800-13464-01	F0	73-5875-04	A0	?
CH57/L/U/SC/15200=	800-13465-01	F0	73-5875-04	A0	?

Problem Description

Customers could experience intermittent bit error bursts on the Cisco ONS 15252/15201 Long Range (+7dBm) Client Layer Interface Port (CLIP) boards. These intermittent errors become more visible at low temperatures (below room temperature).

Background

The problem has been seen in less than one percent of the Long Range CLIPs shipped to customers. The chances that these error bursts will occur are very unlikely under normal operating conditions in a temperature-controlled environment.

Cisco Systems has developed a product improvement that adds a filter to the circuit to prevent laser noise from affecting the call detail record (CDR) circuit. All CLIPs affected, see the Products Affected section, can be returned to Cisco Systems for rework.

Problem Symptoms

Bit error bursts are occasionally introduced in the dense wavelength division multiplexing (DWDM) signal at the transmit side of the Cisco ONS 15252/15201 TX transponder.

The reason for this is that under certain conditions the thermistor pin on the DWDM laser may emit a high frequency noise that causes the clock and data recovery function to fail for a short period. The affected boards are Cisco ONS 15252/15201 Long Range Clips with +7dBm lasers, which emit more high frequency noise than Cisco ONS 15252/15201 Medium Range Clips.

Running the boards at low temperature (0-5 degrees Celsius) increases the frequency of bursts since the laser driver becomes faster, and thereby increases the high frequency noise content.

Workaround/Solution

If you have not experienced any bit error bursts, then no immediate action is required.

To eliminate risk of burst errors, return the Long Range Clips for rework during a scheduled maintenance period. Replacement Clips can be requested from Technical Support; request a return to factory Return Material Authorization (RMA).

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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