Help us improve your experience.

Let us know what you think.

Do you have time for a two-minute survey?

 
ON THIS PAGE
 

Power Redundancy for Third-Generation Power Supply Modules

This topic includes the list of third-generation power supplies that support source and feed redundancy. It also covers configuration and related alarm details.

The following third-generation power supply modules provide N+1 PSM (Power Supply Module) redundancy support:

  • JNP10K-PWR-AC3

  • JNP10K-PWR-DC3

  • JNP10K-PWR-AC3H

Each of these PSMs is equivalent to four power-supplies that consist of four input feeds (A0, A1, B0, and B1) with a maximum power output capacity of 7.8 KW. You can enable redundancy at the source or feed level.

The redundancy feature makes the system more reliable. It enables the system to raise an alarm[1] when the power remaining in the system is less than the power of the connected PSM with the highest capacity.

When a PSM is removed or has a fault in a redundancy-disabled system, the power manager will power off the required FRUs.

See hardware guide for more information about third-gneration PSMs and supported devices.

Note:

Third-generation PSMs cannot provide PSM redundancy in a 4 slot chassis with high power consuming line cards (LCs) such as JNP10K-LC1301.
Note:

The configuration examples and alarms given below are for the devices with Junos OS. On devices with Junos OS Evolved, use psm instead of pem when configuring the redundancy.

Source Redundancy

When you have two power sources (source A and source B), you can enable source redundancy by connecting two sets of independent power feeds from each source to the four input terminals of a third-generation PSM.

Please note the following conditions before configuring the source redundancy:

  • The software currently supports only one redundant source: for example, source A (main source) along with source B (backup or redundant source).

  • The source redundancy is disabled by default. You can use the following CLI command to enable source redundancy:

  • Source redundancy is only applicable if all the PSMs in the system are third generation PSMs. If you try to include a second-generation PSM in the power supply, the system will raise an alarm[2].

  • You must ensure that the feed distribution is even.

  • It is not possible to enable source redundancy and feed redundancy simultaneously. Therefore, you need to disable feed redundancy before enabling source redundancy. To disable feed redundancy, use the following CLI command:

  • You must set the DIP switches to the feed expected position for all four PSM input feeds; otherwise, the system will raise an alarm[3].

Please note the following conditions after configuring the source redundancy feature:

  • The Power Manager considers the capacity of each PSM as a 2-feed capacity. See hardware guide for more information.

  • If one of the sources becomes unavailable, the system will raise an alarm[4] corresponding to the failed feeds. In addition, the system will raise another alarm[3] and disable the source redundancy until the source failure is fixed.

  • The overall system power capacity reduces to protect against a source failure.

  • The software will simulate the feature and determine the new system power capacity. If the system’s new power capacity cannot accommodate the existing system load, the system will disable the source redundancy, raise an alarm[5], and continue to operate in normal mode.

  • When a PSM is faulty and there is no source failure, the system capacity is expected to reduce further. If the reduced system capacity cannot support the existing load, the system will disable the source redundancy, raise an alarm[5], and continue to operate in normal mode. You should replace the failed PSM as soon as possible.

Feed Redundancy

You can enable feed rudundancy by connecting all the four input feeds (A0, A1, B0, and B1) of a third-generation PSM to one or more power sources. When one feed is down, the other feed will continue providing the power and keep the platform operational.

Note:

Feed redundancy is not supported for second-generation PSMs and third-generation active blank power modules. On a Junos OS device, if you try to configure feed redundancy for these unsupported devices, the system will ignore the configuration and make a print available in the LCMD logs. On a Junos OS Evolved device, the system will make the Feed redundancy unsupported for PSM print available in the messages.

Please note the following conditions before configuring the feed redundancy:

  • The PSM must have at least two feeds connected.

  • The software currently supports only one redundant feed.

  • You must set the DIP switches to the feed expected position for both primary and redundant feeds. Otherwise, the system will raise an alarm[6]. Additionally, you must confirm that the DIP switch configuration matches the connected feeds.

  • Feed redundancy is disabled by default. You can use the following CLI command to enable feed redundancy:

  • It is not possible to enable source redundancy and feed redundancy simultaneously. Therefore, you need to disable source redundancy before enabling feed redundancy. To disable source redundancy, use the following CLI command:

Please note the following conditions after configuring the feed redundancy feature:

  • The Power Manager will calculate the capacity of the third-generation PSM by subtracting one feed from the total number of connected feeds. See hardware guide for more information.

  • If the redundant feed becomes unavailable, the system will raise an alarm[4] corresponding to the failed feed. In addition, the system will raise another alarm[7] and disable feed redundancy until the feed failure is fixed.

  • The overall system power capacity reduces to protect against a feed failure.

  • The software will simulate the redundancy feature and determine the system's new power capacity. If the system’s new power capacity is not sufficient to accommodate the existing system load, the system will disable the feed redundancy on a Junos OS device. However, on a Junos OS Evolved device, the system will disable feed redundancy sequentially on PSMs until it achieves the required capacity. Both operating systems will also raise an alarm[8] and continue to operate in normal mode.

  • When a PSM is faulty and there is no feed failure, the system capacity is expected to reduce further. If the reduced system capacity is not sufficient to support the existing load, the system will disable the feed redundancy, raise an alarm[8], and continue to operate in normal mode. You should replace the failed PSM as soon as possible.

Table 1: Power redundancy alarms

Sl No

Message displayed in the output of show chassis alarms command on a Junos OS device

Message displayed in the output of show chassis alarms command on a Junos OS Evolved device

Description

1

No Redundancy

chassis No Redundant Power

Appears when the power remaining in the system is less than the individual connected PSMs.

2

PEM Source Redundancy Unsupported PEM

Unsupported PSM for source redundancy

Appears when you connect an unsupported power supply.

3

PEM Source Redundancy Failure

PSM Source Redundancy Failure

Appears when you do not position the DIP switches for all feeds.

4

PEM %d Feed feed name has no input source

PSM %d Input Feed feed-name Failed

Appears when a source or redundant feed is not available.

5

PEM Source Redundancy Unsupported

No Source Redundancy

Appears when the power is not sufficient after enabling the source redundancy.

6

PEM %d Feed Redundancy Expects Min 2 INP in DIP Switch Cfg

PSM %d Feed redundancy expects min 2 inputs in DIP switch config

Appears when you do not position the DIP switches for all connected feeds.

7

PEM %d FEED REDUNDANCY FAILURE

PSM %d Feed Redundancy Failure

Appears when the feed redundancy is disabled.

8

PEM Feed Redundancy Unsupported

PSM %d Feed Redundancy Unsupported

Appears when the power is not sufficient after enabling the feed redundancy.