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Managing Power

 

Understanding How Dynamic Power Management Enables Better Utilization of Power

You can use the dynamic power management feature to better utilize the power available in the power entry module (PEM). Whether or not a new hardware component is powered on depends on the availability of power in the PEM. A component is not powered on if the PEM cannot meet the worst-case power requirement for that component. The dynamic power management feature is available in the following Junos OS Releases:

  • MX Series routers–Junos OS Release 15.1R1 and later

  • EX9200 switches–Junos OS Release 17.2R1 and later

The maximum power that each type of MIC consumes is maintained in a static database. The chassis daemon process (chassisd), which manages power budgeting for all line cards, uses this data when budgeting power for MICs. MICs are brought online only after the chassis daemon verifies that the worst-case power required for the MICs and the power required for all the online FRUs are available in the PEM.

In Junos OS Release 15.1R1, for MX Series routers, dynamic power management for MICs is disabled by default. You can enable the feature by enabling the mic-aware-power-management statement at the [edit chassis] hierarchy level. When dynamic power management is disabled, the chassis daemon checks for the worst-case power requirement of the MPC and the MICs before allocating power for the MPC. Whereas, when mic-aware-power-management statement is enabled, the chassis daemon considers the power requirement of only the MPCs. The worst-case power consumption by the MICs is not considered while the chassis daemon budgets power for the MPC. Power budgeting for MICs is done only after the MPC is powered on and the MICs come online. Every time you disable or enable dynamic power management, you must restart the chassis or the MPC for the changes to take effect.

In Junos OS Release 17.2R1, for EX9200 switches, dynamic power management for MICs is enabled by default.

Starting from Junos OS Release 17.3R1, for MX10003 routers, mic-aware dynamic power management is enabled by default.

Starting from Junos OS Release 18.2R1, for JNP10K-LC2101 MPC on MX10008 routers, dynamic power management is enabled by default. However, dynamic power management for MICs is not supported on JNP10K-LC2101 because JNP10K-LC2101 is a fixed configuration MPC and supports only built-in PICs.

After you enable the dynamic power management feature, use the set chassis preserve-fpc-poweron-sequence configuration mode command to preserve the sequence in which MPCs are powered on. This configuration is required to maintain the order in which the MPCs come online after a router or switch restart.

Note

In Junos OS Release 15.1F5 and later, dynamic power management is enabled by default on several MPCs. Models include MPC3E-3D-NG, MPC3E-3D-NG-Q, MPC2E-3D-NG, MPC2E-3D-NG-Q, MPC6E, MPC7E-MRATE, and MPC7E-10G on MX240, MX480, MX960, MX2010, and MX2020 and on MPC8E and MPC9E on MX2010, and MX2020 Universal Routing Platforms.

Understanding Power Management on the PTX5000

Starting in Junos OS Release 14.1, the power management feature for PTX5000 routers ensures that at any time, the chassis power requirements do not exceed the available chassis power. The PTX5000 has two PDUs to meet the power requirements of the chassis. Each PDU is capable of providing power to the chassis on its own. In case the power requirement exceeds the individual capacity of a PDU, the required power is provided by both the PDUs and the No redundant power supply alarm is triggered. If the system cannot provide power for all the installed FPCs or PICs, the system brings down FPCs or PICs that in can no longer provide power for and the Insufficient Power - FRU(s) went offline alarm is raised.

The power management feature provides the following functionality:

  • Power management ensures that high-priority FPCs continue to receive power when the system does not have sufficient power to keep all the FPCs online.

  • Power management ensures that if a power supply fails, the router can continue to operate normally by keeping high-priority FPCs online and taking low-priority FPCs offline.

  • If power supply failure requires power management to power down some components, power management does so by gracefully powering down lower-priority FPCs.

Power management manages power to router components by employing a power budget policy. In its power budget policy, power management:

  • Budgets power for each installed router component that requires power. The amount that power management budgets for each component is the maximum power that component might consume under worst-case operating conditions. For example, for the fan tray, power management budgets the amount of power required to run the fans at their maximum speed setting, even if the current fan speed is much lower.

  • Manages the router for N+N power redundancy, which ensures uninterrupted system operation if one power supply fails.

  • Provides power to host subsystem components, such as the Routing Engines, before it provides power to the FPCs.

  • Manages the priority of individual FPCs. By assigning different priorities to the FPCs, you can determine which FPCs are more likely to receive power in the event of insufficient power.

Power Priority of FPCs

The power priority of FPCs determines:

  • The order in which FPCs are allocated power.

  • How power is reallocated if there is a change in power availability or demand in an operating router.

This section covers:

How an FPC’s Power Priority Is Determined

Using the CLI, you can assign an explicit power priority to an FPC slot. The power priority is determined by the slot number, with the lowest-numbered slots receiving power first. Thus, if you do not explicitly assign priorities to slots, power priority is determined by slot number, with slot 0 having the highest priority. See Configuring Power-On Sequence to Redistribute the Available Power.

FPC Priority and FPC Power Allocation

When a PTX5000 is powered on, power management allocates power to components according to its power budget policy. After power management has allocated power to the host subsystem components, it allocates the remaining available power to the FPCs. It powers on the FPCs in the configured order of priority until all FPCs are powered on or the available power provided by both the PDUs is exhausted. Thus if available power is exhausted before all FPCs receive power, higher-priority FPCs are powered on while lower-priority FPCs remain powered off.

FPCs that have been taken offline are not allocated power.

Note

Because power management does not allocate power to an FPC that has been taken offline, that FPC is brought online only when you commit a configuration. You must explicitly use the request chassis fpc slot slot-number online command to bring an FPC online that was taken offline previously.

If an FPC with a high priority in the priority sequence also has high-power requirement, and if the system does not have the required power available, then the lower priority FPCs with lower power requirements are also not powered on. This is to maintain consistency and also avoid powering off of the lower priority FPC when extra power is available. For example, if an FPC that requires 450 W has a higher priority than an FPC that requires 330 W, then the FPC with the lower power requirement (330 W) is also not powered on if the system does not have the required power to power the FPC that requires 450 W.

FPC Priority and Changes in the Power Budget

In an operating router, power management dynamically reallocates power in response to changes in power availability or demand or changes in FPC priority. Power management uses the configured priority on FPC slots to determine how to reallocate power in response to the following events:

  • When a new power supply is brought online, FPCs that were powered off because of insufficient power are powered on in the order of priority.

  • When a user changes the assigned power priority of one or more FPCs when power is insufficient to meet the power budget, power management reruns the current power budget policy and powers FPCs on or off based on their priority. As a result, FPCs receive power strictly by the order of priority and previously operating FPCs might no longer receive power.

  • When an FPC is installed, Junos OS does not automatically power on and bring the FPC online. This FPC stays in the offline state until the user brings it online through the CLI or by pushing the online button, and only if the available chassis power is more than the budgeted power for this FPC, the FPC becomes operational.

Power Zones

In a PTX5000 equipped with high capacity PDUs and PSMs, there in one common zone that provides power to all FRUs and all FPCs. A high-capacity PDU can support up to eight PSMs and it does not support power zoning, unlike a normal-capacity PDU. All available PDU power is considered as a part of single zone. All PSMs provide power to the common zone. The PSM LEDs on the craft interface are interpreted as described in PTX5000 Craft Interface LEDs. After the PDU upgrade from the normal-capacity PDUs to High-Capacity PDUs, the power management converges all power zones into a single common zone. All FRU power is distributed based on the power available in the common zone.

Note

Presence of both normal-capacity PDUs and high-capacity PDUs is referred to as mixed-mode of operation and is supported only during the PDU upgrade.

To cater for the increase in the PIC power consumption, the power manager is enhanced to account for the PIC power separately from the FPC. The priority sequence for the PICs follows the priority sequence for the FPCs. That is, PICs installed in high-priority FPCs are given preference over PICs installed in low-priority FPCs. All PICs on an FPC have the same priority.

Note

You cannot mix existing PDUs with the High Capacity DC PDU.

Power Supply Redundancy

By default, power management in PTX5000 routers is configured to manage the power supplies for N+N redundancy, by which power supplies are held in reserve for backup if the other power supplies are removed or fail.

When power is insufficient to meet the budgeted power requirements, power management raises alarms as follows:

  • With power supply redundancy, when one PSM fails, it does not cause FPCs to go offline. Only the No redundant power supply alarm is raised. However, with no redundancy, FPCs can go offline depending on the total chassis power available at that time. When an FPC or PIC goes offline due to insufficient power, which is indicated by No power in the output of the show chassis fpc command, then the Insufficient Power - FRU(s) went offline alarm is raised. The alarm gets cleared when there is sufficient power to bring up all the FPCs and PICs. The Insufficient Power - FRU(s) went offline alarm is raised when PSMs fail, when PSMs are powered off manually, or any time there is insufficient power for the system to power all the FPCs or PICs in the system.

  • When power fails or when a PSM is removed, power management:

    • Calculates the total chassis power available from the remaining PSMs for the FPCs.

    • Powers off the FPCs based on the priority depending on the power budget for the FPCs and the FRUs and their configured power-on sequence.

      Note

      In the scenario where the available power is more than the budgeted power required by the FPC but less than its maximum power, the FPC is taken offline and then brought online, but one or more PICs in that FPC are not online.

  • When a new PSM is inserted, power management:

    • Checks the power-on sequence of the FPCs and the PICs and brings any offline PICs online when power is available.

    • Powers on the FPCs based on the FPC’s budgeted power and its power-on sequence depending on its priority.

    • Maintains the power for high-priority FPCs and their PICs by taking the low-priority FPCs offline when all the FPCs are brought online, depending on the available power.

Power management clears all alarms when sufficient power is available to meet normal operating and reserved power requirements.

T4000 Power Management Overview

Starting with Junos OS Release 12.3, the power management feature is enabled on a Juniper Networks T4000 Core Router. This feature enables you to limit the overall chassis output power consumption. That is, this feature enables you to limit the router from powering on a Flexible PIC Concentrator (FPC) when sufficient output power is not available to power on the FPC during booting or normal operation.

The power management feature is enabled only when six input feeds with 40 amperes (A) each or four input feeds with 60 A each is configured on the router. The power management feature is not enabled for any other input feed–-current combination. When the power management feature is not enabled, Junos OS tries to power on all the FPCs connected to the router.

Caution

: If you do not configure the power management feature and the maximum power draw is exceeded by the router during booting or normal operation, FPCs’ states might change from Online to Offline or Present, some traffic might drop, or the interfaces might flap.

Tip

Interface flapping occurs when a router alternately announces the state of the interface to be as up and down in quick sequence.

After you connect the input feeds to the router, you must configure the number of input feeds connected to the router and the amount of current received at the input feeds. Use the feeds statement and the input current statement at the [edit chassis pem] hierarchy level to configure the number of input feeds and the amount of current received at each input feeds, respectively.

Note

You can connect three 80 A DC power cables to the six-input DC power supply by using terminal jumpers. When you do this, ensure that you configure the feeds statement to have the value 6 and the input current statement to have the value 40. If these configurations are not set, the power management feature is not enabled and, therefore, Junos OS tries to power on all the FPCs connected to the router.

When the power management feature is enabled, FPCs connected to the router are powered on based on the power received by the router. If the router receives sufficient power to power on all the FPCs connected to the router, all the FPCs are powered on. If sufficient power is not available, Junos OS limits the number of FPCs brought online. That is, Junos OS uses the total available chassis output power as a factor to decide whether or not to power on an FPC connected to the router.

Of all the supported FPCs of a T4000 router, the T1600 Enhanced Scaling FPC4 (model number: T1600-FPC4-ES) has the greatest power requirement.Table 1 compares the FPC connection limits between a six-input feed 40 A connection and a four-input feed 60 A connection when power management is enabled and T1600-FPC4-ES is connected to router.

Table 1: FPC Connection Limit Comparison

Six Input Feeds with 40 A Connection

Four Input Feeds with 60 A Connection

When T1600-FPC4-ES is not connected:

  • All eight FPC slots can be brought online.

When T1600-FPC4-ES is not connected:

  • A maximum of seven other FPCs can be brought online. That is, only seven slots out of the eight FPC slots can be brought online.

When only one T1600-FPC4-ES is connected:

  • A maximum of seven other FPCs can be brought online. That is, only seven slots out of the eight FPC slots can be brought online.

When only one T1600-FPC4-ES is connected:

  • A maximum of six other FPCs can be brought online. That is, only six slots out of the eight FPC slots can be brought online.

When only T1600-FPC4-ES FPCs are connected:

  • A maximum of six T1600-FPC4-ES FPCs can be brought online.

More than one T1600-FPC4-ES cannot be brought online.

Note
  • When the power management feature is enabled, FPC power-on consistency is not maintained across router reboots. That is, the same set of FPCs that were powered on before a reboot might not be powered on after the reboot. Before the router reboot, the FPCs are powered on according to their insertion order in the chassis. After the reboot, the FPCs are powered on according to the FRU power-on sequence configured in the fru-poweron-sequence statement at the [edit chassis] hierarchy level. If the FRU power-on sequence is not configured, Junos OS uses the ascending order of the slot numbers of the FPCs as the sequence to power on the FPCs.

  • Removal of any online FPC from the chassis does not change the state of any other FPC and does not trigger the power management feature to power on the FPCs that were not powered on initially because of the lack of sufficient power. When any online FPC is removed from the chassis, if you need to trigger the power management feature to re-evaluate the situation, you need to reboot or restart the chassis. Alternatively, you can make a configuration change at the [edit chassis] hierarchy level and then issue the commit command to commit the changes made at the [edit chassis] hierarchy level. The power management feature to re-evaluates the situation when a configuration change is committed at the [edit chassis] hierarchy level.

Configuring the Six-Input DC Power Supply on T Series Routers

By default, the six-input DC power supply is configured to have all the six input feeds connected. You can also choose to provide four or five input feeds to the six-input DC power supply. When providing four or five input feeds on standalone routers, you need to configure the feeds statement at the [edit chassis pem] hierarchy level. When providing four or five input feeds to an LCC router in a routing matrix, you need to configure the feeds statement at the [edit chassis lcc lcc-number pem] hierarchy level.

Starting with Junos OS Release 12.3, the power management feature is enabled on T4000 routers with six-input DC power supply. The power management feature is enabled only when six input feeds with 40 amperes (A) each or four input feeds with 60 A each is configured on the router. To do this, you need to configure the feeds and input-current statements at the [edit chassis pem] hierarchy level.

Note
  • Before configuring input feeds for your router, see the T640 Core Router Hardware Guide, T1600 Core Router Hardware Guide, or T4000 Core Router Hardware Guide for special considerations and for the number of input feeds supported by the router.

  • The value assigned to the feeds statement must be equal to the number of input feeds provided to the power supply. Else, an alarm message is generated to indicate the mismatch.

The following procedures describe how to configure the six-input DC power supply on different routers:

Configuring the Six-Input DC Power Supply on an LCC Router in a Routing Matrix

To configure the six-input DC power supply on an LCC router in a routing matrix:

  1. At the [edit chassis lcc lcc-number pem] hierarchy level, configure the feeds statement with the number of input feeds provided to the power supply.

    For example:

    Note

    All power supplies in the router must use the same number of inputs feeds.

  2. Verify the configuration by using the show command at the [edit chassis] hierarchy level:

Configuring the Six-Input DC Power Supply on T640 and T1600 Routers

To configure the six-input DC power supply on a standalone T640 or T1600 router:

  1. At the [edit chassis pem] hierarchy level, configure the feeds statement with the number of input feeds provided to the power supply.

    For example:

    Note

    All power supplies in the router must use the same number of inputs feeds.

  2. Verify the configuration by using the show command at the [edit chassis] hierarchy level:

Configuring the Six-Input DC Power Supply on T4000 Routers

To configure the six-input DC power supply on a T4000 router:

  1. At the [edit chassis pem] hierarchy level, configure the feeds statement with the number of input feeds provided to the power supply.

    For example:

    Note

    All power supplies in the router must use the same number of inputs feeds.

  2. Configure the input current received by the router.

    For example, if the router receives 60 A of input current:

    Note

    You can connect three 80 A DC power cables to six-input DC power supply by using terminal jumpers. When you do this, ensure that you set the value of the feeds statement to 6 and that of the input current statement to 40. If these configurations are not set, the power management feature is not enabled. For more information about the power management feature, see T4000 Power Management Overview.

  3. Verify the configuration by using the show command at the [edit chassis] hierarchy level:

Redistributing the Available Power by Configuring Power-On Sequence

Routers running on Junos OS Release 10.0 and later support an enhanced AC Power Entry Module (PEM) to provide the necessary power infrastructure to support up to twelve higher-capacity DPCs with higher port density and slot capacity. To support the cooling requirements for the enhanced AC PEMs, the routers support enhanced fan trays and fans.

The default behavior for MPC power-on sequence is slot number based, that is, slot 0 is brought online first followed by slot 1, slot 2 up to slot 11. For the scenarios, where it is running a mix of high capacity line cards (for core facing), and low capacity line cards (for access facing) in their system, you can use the fru-poweron-sequence option to manually set the MPC power on sequence and hence ensure that the more important core facing line cards are brought online first irrespective of which slots these are in. This approach provides fine control over deterministically bringing up MPCs, however, it is heavy on configuration and entails to follow the discipline in slot to MPC mapping across all the systems.

The Junos OS enables you to configure the power-on sequence for the DPCs on an MX Series router chassis containing the new AC PEM. This enables you to redistribute the available power to the DPCs based on your requirements and the calculated power consumption of the DPCs. To configure the power-on sequence, refer to Configuring Power-On Sequence to Redistribute the Available Power.

Configuring Power-On Sequence to Redistribute the Available Power

You can configure the power-on sequence for the Flexible PIC Concentrators (FPCs) on MX, PTX, and T routers. This configuration enables you to redistribute the available power to the FPCs on the basis of your requirements and the calculated power consumption of the FPCs.

To configure the power-on sequence:

  1. At the [edit chassis] hierarchy level, configure the fru-poweron-sequence statement indicating the order in which the FPCs need to be powered on.

    For example:

  2. Verify the configuration by using the show command at the [edit chassis] hierarchy level:
Note
  • If the configured sequence contains invalid numbers, Junos OS considers only the valid numbers in the sequence. The invalid numbers are silently discarded.

  • If the power-on sequence is not configured by including the fru-poweron-sequence statement, Junos OS uses the ascending order of the slot numbers of the FPCs as the sequence to power on the FPCs.

  • Issue the show chassis power command to view power limits and usage details for the FPCs.

Configuring Voltage Level Monitoring of FPCs

You can monitor the voltage on the flexible PIC concentrator (FPC) at regular intervals. When the voltage falls below 10%, the FPC is offlined.

The faulty FPC is monitored at 500ms intervals. The output of the show chassis fpc command shows Power Failure for the faulty FPC. The FPC remains in powered down state until the voltage level is normal again.

Enabling Voltage Failure Errors on the FPC

fpc-nmi-volt-fail-knob controls the behavior of the FPC after detecting voltage failure, and to online or offline the FPC based on the voltage level. To enable monitoring the voltage level on the FPC:

  1. Navigate to the [edit chassis] hierarchy level.

  2. Include the set chassis fpc-nmi-volt-fail-knob enable statement to enable voltage monitoring on the FPC.

Disabling Voltage Failure Errors on the FPC

To disable monitoring the voltage level on the FPC:

  1. Navigate to the [edit chassis] hierarchy level.

  2. Include the set chassis fpc-nmi-volt-fail-knob disable statement to disable voltage monitoring on the FPC.

Release History Table
Release
Description
Starting from Junos OS Release 18.2R1, for JNP10K-LC2101 MPC on MX10008 routers, dynamic power management is enabled by default.
Starting from Junos OS Release 17.3R1, for MX10003 routers, mic-aware dynamic power management is enabled by default.
EX9200 switches–Junos OS Release 17.2R1 and later
In Junos OS Release 17.2R1, for EX9200 switches, dynamic power management for MICs is enabled by default.
MX Series routers–Junos OS Release 15.1R1 and later
In Junos OS Release 15.1R1, for MX Series routers, dynamic power management for MICs is disabled by default.
In Junos OS Release 15.1F5 and later, dynamic power management is enabled by default on several MPCs.
Starting in Junos OS Release 14.1, the power management feature for PTX5000 routers ensures that at any time, the chassis power requirements do not exceed the available chassis power.