Description

This KB describes a scenario when a major alarm "PEM <> Unrecognized for the platform" is reported on ACX5448 and clarifies whether any action should be taken to resolve this issue.

Symptoms

New ACX5448 installed onto network, having major alarms as follows:

device> show chassis alarms
2 alarms currently active
Alarm time Class Description
2023-09-07 00:36:15 BST Major PEM 0 Unrecognized for the platform
2023-09-07 00:36:15 BST Major PEM 1 Unrecognized for the platform
device> show chassis hardware | grep PEM
PEM 0 REV 06 740-041741 1F16B312051 JPSU-650W-AC-AFO
PEM 1 REV 06 740-041741 1F16B312412 JPSU-650W-AC-AFO

Solution

Please check chassisd log:

CHASSISD_I2C_INVALID_ASSEMBLY_ID: '0x0466' is invalid value for RIO series PEM assembly ID

And output of "show chassis hardware extensive":

PEM 1      REV 06  740-041741  1GA2B080693    JPSU-650W-AC-AFO
<...>
Assembly ID: 0x0466      Assembly Version: 07.06
According to the Juniper official website, JPSU-650W-AC-AFO is not compatible with ACX5448, although it might be working just fine. The following AC PSM modules are compatible (please refer to ACX5448, ACX5448-D, and ACX5448-M Power System for more information):
  • JPSU-650W-AC-AI
  • JPSU-650W-AC-AO

Modification History

2024-10-01: Major formatting changes, made this KB public.
2023-09-14: Initial draft.