Cisco 6400 Series Broadband Aggregators

Cisco 6400 NSP Card Can Fail When a DC Voltage Greater than -48 Volts Is Applied

March 4, 2002

Products Affected


Top Assembly


HW Rev.

Part Number



Cisco 6400 Node Switch Processor




Cisco 6400 Node Switch Processor Bundle




Cisco 6400 Redundant Node Switch Processor




Cisco 6400 NSP with Stratum 3/BITS




Cisco 6400 Redundant Node Switch Processor with Stratum


? ?

Note:?Spares of these parts at the same revision level will also be affected. Spares are designated by the "=" sign.


Problem Description

The Cisco 6400 Node Switch Processor (NSP) fails when greater than -48 Volts DC (VDC) is applied, causing the system to crash.


The Cisco 6400 is rated for an input DC voltage of -40.5 VDC to -72 VDC. This voltage range is provided to cover all possible cases of Central Office (CO) power. The vast majority of customers use -48 VDC. It was discovered by a customer using -60 VDC that a diode in the NSP power circuit was undersized and will fail over time when using a voltage greater than -48 VDC.

Problem Symptoms

The NSP will work normally for a period of time and then lose power without warning. The loss of power on the NSP will cause the entire Cisco 6400 to shut down if only one NSP is being used. If redundant NSPs are being used then the system will continue to operate when the affected NSP loses power.

Note:?The redundant NSP will still be susceptible to this problem and will eventually fail in the same manner causing a system shutdown. Make sure that both the primary and redundant NSPs are upgraded if using greater than -48 VDC to power the Cisco 6400.


There is no workaround. The solution to this issue is to replace the NSP card using the Return Materials Authorization (RMA) process.

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: