problem with RPS 675

[ippolito]

Hello, we have the following problem with the RPS 675:  when power is cut to a switch (I've tried with 3750-48 and 3750G-24), the RPS successfully begins supplying power to the switch with no loss of service.  However, when power is restored to the main power supply, a "show env all" indicates that the power supply is "Unavail", while the RPS is still supplying power.  If the RPS is put into standby mode, the switch reboots.  Is that by design?  It would seem that when power is restored to the switch's main power supply and the RPS put into standby, the switch should resume using power from its main supply.  Any help on this would be greatly appreciated.

thanks,

Mike

[Arumugam Muthaiah · Accepted solution]

Hi Mike,

This is the expected behavior

The internal power supply on the Catalyst switch was connected to one power source, and the RPS was connected to the same or different power source as the switch. The power source connected to the internal power supply failed, causing the RPS to supply power to the switch. (The power to the RPS did not fail either because that circuit did not fail, the RPS was connected to an Uninterruptible Power Supply (UPS), etc.)

After some period of time, the power connected to the internal power supply comes back online for whatever reason, and the RPS675 continues to back up the switch and dominate the switch's internal power supply (it will not back off automatically if the switch power supply restores itself).

Then the mode button on the RPS is pressed to put the RPS in standby mode. When the switch changes from RPS power back to the internal power supply, there is a possibility that the switch might reload.

Suggestion:

To prevent unscheduled downtime, the switch should be powered off during a maintenance window.

Additional Information:

1. The RPS is a Redundant Power Supply, not an Uninterruptible Power Supply.

2. The RPS is designed to protect from a failure of the internal power supply in a switch, not the failure of a power circuit.

3. This problem might occur on some switches, might not occur on other switches, and might occur intermittently on the same switch.

4. The switch does NOT reload when switching from the internal power supply to the RPS.

Refer:

http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps7148/ps5066/product_data_sheet09186a0080150e31_ps628_Products_Data_Sheet.html

Regards,

Aru

[ippolito]

Thanks very much for the information.

Mike