Description

This article highlights the reason an FPC may not come online during and RE/SCB upgrade.

Symptoms

FPC shows as offline and alerts of insufficient power: 

root@srx>show chassis alarms no-forwarding
 
1 alarms currently active
Alarm time               Class  Description
2020-09-24 04:20:30 EEST Major  Power Budget:Insufficient Power
Chassisd logs show the following: 
Sep 24 04:53:13 LCC: FPC 5 is requesting power (consumption) 585W, total remaining pwr 580

Sep 24 04:53:13 LCC: ch_fru_power_sequencer FPC 5 step 0
Sep 24 04:53:13 LCC: FPC 5 is requesting power (consumption) 585W, total remaining pwr 580
Sep 24 04:53:13 LCC: send: red alarm set, device Power Supply, reason Power Budget:Insufficient Power
Sep 24 04:53:13 CHASSISD_FRU_OFFLINE_NOTICE: Taking FPC 5 offline: No power​

Solution

When RE/SCB upgrade is done, usually the SCB, for example, SCB3 will use higher power compared to previous version of SCB. In that case, when the chassis boots up, it may need to draw additional power. As a result, one of the FPC, usually the last one in the affected zone, may end up getting insufficient power and will not come online.

This is an expected behavior. Below is the power requirement and power budget calculation for ​SCB3 as an example:

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  1. Calculate the power distribution with the new RE/SCB and check if any FPC is falling short of power on the respective zone. The following guide can be used:
    Calculating Power Requirements for the SRX5800 Services Gateway

  2. Move the card to another slot in another zone as applicable.

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