Description

This article explains why when PEM0 and PEM2 fails, CB1, CB2 and FPC7 to FPC11 along with lower fan tray may not boot up.
 

Symptoms

When PEM0 and PEM2 fail, CB1, CB2 and FPC7 to FPC11 may not boot up and there would be other series of events like I2C failures for these FRUs.

 

Solution

As per official Juniper documentation, PEM0 and PEM2 act as redundant power supplies to supply power to FRUs - Lower Fan tray, FPC 6 to 11 (FPC6 in case if it used in slot 6 or CB2 if CB is inserted in slot 6). and CB1 and CB2.

So, if both PEM0 and PEM2 fail, these FRUs will experience issues in booting up and may be accompanied by I2C access failures for these FRUs

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Modification History

2024-03-24 : Article Created