PTX10004 supports a maximum of 3 *PSMs for N+1 (2+1) redundancy.

The customer installed 3 * LC1201 and they are up online ok.

When the customer inserted the 4th LC1201 FPC, the following alarm was raised:

PTX10004-re0> show system alarms

1 alarms currently active

Alarm time Class Description

2025-10-28 06:16:55 UTC Major chassis No Redundant Power

This alarm is expected.

Take an example of JNP10K-PWR-DC2 power supplied.

The reason is PTX10004 with 3 * PSMs. In the default 2+1 redundancy mode, each PSM is 5,500W, and the max output is 11,000W (2*5,500W) for N+1 redundancy.

3,750W of the 11,000W is reserved for non-FPC FRUs like RCB(RE/CB), SIBs and other parts in the system.

The remaining 7,250W ( 11,000W - 3,750W =7,250W) is available for FPC Line-cards.

Each LC1201 FPC costs 2,360W at most, with 7,250W we can support max 3*LC1201 (3*2,360W = 7,080W ) in 2+1 redundancy mode.

With the 4th LC1201 FPC added, it will need around 2,360W*4 = 9,440W to work in redundancy 2+1 mode, but we only have max 7250W for FPCs in 2+1 redundancy mode.

So we have to use all 3*PSMs without redundancy to provide enough power to online all 4*LC1201 FPCs (3*5,500W - 3750W = 12,750W > 9,440W required) 

Since we lost power supply redundancy, the system will alarm ”Chassis No Redundant Power”.