Technical Documentation

Example: Configuring PoE Interfaces on an EX Series Switch

Power over Ethernet (PoE) ports supply electric power over the same ports that are used to connect network devices and allow you to plug in devices that require both network connectivity and electric power, such as VoIP phones, wireless access points, and some IP cameras. For EX Series switches that support PoE ports, the factory default configuration specifies PoE interfaces for the PoE ports. Therefore, you do not need to configure PoE unless you wish to modify the default values or disable a specific PoE interface.

Note: The default power management mode is static mode. On a Juniper Networks EX2200 Ethernet Switch with 48 PoE ports, we recommend that you change the power management mode to class mode. On an EX2200 switch, the total power available to all PoE ports is 405 W. Under the default static mode settings, PoE power management reserves 15.4 W for each port, which means only 26 ports receive power. Given the default priority settings, the 26 ports that receive power are the first 26 ports.

In class mode, on the other hand, the power provided to the port is determined entirely by the power demand of the device. Thus in class mode, any PoE port can be used to power a device and all 48 ports can be used as long as the combined power demand does not exceed 405 W. See Configuring PoE (CLI Procedure) for information on how to configure class mode.

This example describes a default configuration of PoE interfaces on an EX Series switch:

Requirements

This example uses the following software and hardware components:

  • JUNOS Release 9.0 or later for EX Series switches
  • One EX4200 switch

Before you configure PoE, be sure you have:

Overview and Topology

The topology used in this example consists of one EX4200-24T switch, which has a total of 24 ports. Eight of the ports support PoE, which means they provide both network connectivity and electric power for devices such as VoIP phones, wireless access points, and some IP security cameras. The remaining 16 ports provide only network connectivity. You use the standard ports to connect devices that have their own power sources, such as desktop and laptop computers, printers, and servers. Table 1 details the topology used in this configuration example.

Table 1: Components of the PoE Configuration Topology

PropertySettings

Switch hardware

EX4200-24T switch, with 24 Gigabit Ethernet ports: 8 PoE interfaces (ge-0/0/0 through ge-0/0/7) and 16 non-PoE interfaces (ge-0/0/8 through ge-0/0/23)

VLAN name

default

Connection to a wireless access point (requires PoE)

ge-0/0/0

Connections to Avaya IP telephone—with integrated hub, to connect phone and desktop PC to a single port (requires PoE)

ge-0/0/1 through ge-0/0/7

Direct connections to desktop PCs, file servers, integrated printer/fax/copier machines (no PoE required)

ge-0/0/8 through ge-0/0/20

Unused ports (for future expansion)

ge-0/0/21 through ge-0/0/23

Configuration

To enable the default PoE configuration on the switch:

CLI Quick Configuration

By default, PoE interfaces are created for all PoE ports and PoE is enabled. You can simply connect powered devices to the PoE ports.

Step-by-Step Procedure

To use the PoE interfaces with default values:

  1. Make sure the switch is powered on.
  2. Connect the wireless access point to switch interface ge-0/0/0.
  3. Connect the eight Avaya phones to switch interfaces ge-0/0/1 through ge-0/0/7.

Verification

To verify that PoE interfaces have been created and are operational, perform this task:

Verifying That the PoE Interfaces Have Been Created

Purpose

Verify that the PoE interfaces have been created on the switch.

Action

List all the PoE interfaces configured on the switch:

user@switch> show poe interface
                        
Interface Enabled status max-power priority power-consumption Class ge-0/0/0 Enabled ON 15.4W Low 12.95W 0 ge-0/0/1 Enabled ON 15.4W Low 12.95W 0 ge-0/0/2 Enabled ON 15.4W Low 12.95W 0 ge-0/0/3 Enabled ON 15.4W Low 12.95W 0 ge-0/0/4 Enabled ON 15.4W Low 12.95W 0 ge-0/0/5 Enabled ON 15.4W Low 12.95W 0 ge-0/0/6 Enabled ON 15.4W Low 12.95W 0 ge-0/0/7 Enabled ON 15.4W Low 12.95W 0

Meaning

The show poe interface command lists PoE interfaces configured on the switch, with their status, priority, power consumption, and class. This output shows that eight interfaces have been created with default values and are consuming power at the expected rates.

Troubleshooting

Troubleshooting PoE Interfaces

Problem

The PoE port is not supplying power to the port.

Solution

Check for the following:

Items to CheckExplanation

Is the switch a full PoE model or partial PoE model?

If you are using a partial PoE model, only interfaces ge-0/0/0 through ge-0/0/7 can function as PoE ports.

Has the PoE interface been disabled for that port?

Use the show poe interface command to check PoE interface status.

Is the cable properly seated in the port socket?

Check the hardware.

Enable telemetries for the interface.

Check the history of power consumption on the interface by using the show poe telemetries interface command.


Published: 2010-08-19

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