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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.
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, 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 FPCss 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:
| When T1600-FPC4-ES is not connected:
|
When only one T1600-FPC4-ES is connected:
| When only one T1600-FPC4-ES is connected:
|
When only T1600-FPC4-ES FPCs are connected:
| More than one T1600-FPC4-ES cannot be brought online. |
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