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EX Series Redundant Power System Hardware Overview

You can use the EX Series Redundant Power System (RPS) to provide backup power for Juniper Networks EX2200 Ethernet Switches, (except Juniper Networks EX2200-C Ethernet Switches) and Juniper Networks EX3300 Ethernet Switches that are standalone switches or are members of a Virtual Chassis.

Most EX Series switches have a built-in capability for redundant power supplies—therefore, if one power supply fails on those switches, the other power supply takes over. However, EX2200 switches and EX3300 switches have only one internal fixed power supply. If an EX2200 switch or EX3300 switch is deployed in a critical situation, we recommend that you connect a an RPS to that switch to supply backup power during a loss of power.

RPS is not a primary power supply—it only provides backup power to switches when the single dedicated power supply fails. An RPS operates in parallel with the single dedicated power supplies of the switches connected to it and provides all connected switches enough power to support either Power over Ethernet (PoE) or non-PoE devices when the power supplies on the switches fail.

An RPS can hold up to three power supplies connected to as many as six switches—how that power is allocated is up to you. You determine whether or not to connect switches that provide PoE and you determine which switches have priority. Priority becomes an issue when you connect more than three switches that provide PoE to a fully loaded RPS because a switch providing PoE requires more power than a switch that does not provide PoE. Because a power supply can support only one switch providing PoE, the RPS can become oversubscribed when too many switches that must have enough power for PoE have a power failure.

Benefits of the EX Series Redundant Power System

Provides power backup—You connect up to six EX2200, EX3300, or a combination of these switches and supply power to any three of them.

Protection from high-voltage input and short circuits—RPS provides protection from high-voltage input and short circuits.

Switch Models and Configurations Supported by the RPS

The RPS supports all EX3300 switches and EX2200 switches except EX2200-C switches. You can simultaneously connect any supported switches to the same RPS, whether the switches are standalone switches or are configured in a Virtual Chassis.

All power provided by RPS is either PoE or non-PoE. By default, RPS supports switches that provide PoE. If even one switch provides PoE, then the RPS must be configured to provide enough power for PoE. When enough power for PoE is supplied, one switch can be powered by each power supply. If the switches are not providing PoE power, two switches can be powered by one RPS power supply—you can reconfigure an RPS to provide non-PoE power using a feature called multi-backup.

Table 1 lists some possible scenarios and RPS solutions. These examples assume that each RPS is fully loaded with three power supplies.

Table 1: Sample Requirements and RPS Solutions

Switches Requiring Backup

You need this RPS configuration:

Six switches that do not provide PoE to attached devices

One RPS can simultaneously provide power to all six switches if you change the power default to multi-backup—this indicates that no attached switch provides PoE to any devices.

One switch that provides PoE to other devices or two switches that do not provide PoE to any devices

One RPS will always back up all three switches, whether or not they provide PoE to connected devices. Leave the power at the default setting (no multi-backup) and let RPS determine that two switches need only minimum power and one switch provides PoE and therefore needs extra power. RPS automatically supplies the correct level of power.

One EX Series Virtual Chassis member that supplies PoE, one switch that supplies PoE, and one switch that does not supply PoE to any connected devices

One RPS will always back up all three switches. Leave the power default setting (no multi-backup) and let RPS determine that one switch needs only minimum power, one switch needs extra power because it supplies PoE, and the Virtual Chassis member also provides PoE to connected devices.

One switch that supplies PoE and five switches that do not supply PoE

You have two options.

Option 1—Use one RPS: Up to three switches that do or do not supply PoE can be backed up simultaneously. You can prioritize the six switches to determine which three are most important if all six fail at once. You must leave the power default setting (no multi-backup) because you have one switch that supplies PoE to attached devices and therefore requires more power.

Option 2—Use Two RPSs: In this case, you can connect three switches to each RPS and all switches will be backed up if they all fail at once. Alternatively, you can change the power default to multi-backup on one RPS and connect all five switches that do not supply PoE to that RPS, leaving the other RPS to back up the switch that supplies PoE.

EX Series Virtual Chassis

Use as many RPSs as needed to back up all members of the Virtual Chassis.

When a Switch’s Power Supply Fails

Because the power supplies for both EX3300 switches and EX2200 switches are internal, if the switch’s power supply fails, you must replace the switch. You should remove or replace a switch with a failed power supply as soon as possible.

Do not try to use an RPS as a primary power supply because an RPS cannot boot or reboot a switch. Each switch connected to the RPS must have its own dedicated power supply and must have booted up using the internal power supply.

If a switch is deployed in a large network center where RPS has a separate source of electricity than the switches it supports, the RPS supplies power when only the switch’s electricity fails. In this case, you would not have to replace the switch because the power supply is still functional. The switch will resume using its own internal power supply when electricity to the switch is restored.

Components of the RPS

Table 2 lists and describes the components of an RPS:

Table 2: Redundant Power System Components

Component

Value

Power supplies that can be installed

Up to three EX-PWR3-930-AC power supplies. One is included and additional power supplies must be ordered separately.

Switch connector ports on RPS

6 (2 per power supply)

Power cords

(for connecting power supplies to the AC power source outlet)

Up to three power cords, one per power supply.

RPS cables

(for connecting a switch to a power supply installed in the RPS)

6 (1 for each RPS-to-switch connection). One cable is supplied with the RPS. Additional cables must be ordered separately.