Technical Documentation

SRX240 Services Gateway Power over Ethernet Overview

Introduction

Power over Ethernet (PoE) provides the capability for both data and electric power to pass over a copper Ethernet LAN cable.

The SRX240 Services Gateway supports PoE on all Gigabit Ethernet ports. The PoE ports transfer electrical power, along with data, to remote devices over standard twisted-pair cable in an Ethernet network. PoE ports allow you to plug in devices that require both network connectivity and electric power, such as wireless LAN access points, and VoIP telephones.

You can configure the services gateway to act as power sourcing equipment for devices connected on the designated ports.

Table 1 lists the SRX240 Services Gateway PoE specifications.

Table 1: SRX240 Services Gateway PoE Specifications

Power Management Schemes

Values

Supported standards

  • IEEE 802.3 AF
  • IEEE 802.3 AT (PoE+)
  • Legacy (pre-standards)

Supported ports

PoE is supported on all 16 Gigabit Ethernet ports (ge-0/0/0 to ge-0/0/15)

Total PoE power sourcing capacity

150 watts

Per port power limit

30 watts

Note: Default value is 15.4 watts

Power management modes

  • Static: Power allocated for each interface can be configured.
  • Class: Power allocated for interfaces is decided based on the class of powered device connected.

PoE Classes and Power Ratings

A powered device is classified based on the maximum power that it draws across all input voltages and operational modes. When class-based power management mode is configured on the services gateway, power is allocated taking into account the maximum power ratings defined for the different classes of devices.

Table 2 lists the classes and their power ratings as specified by the IEEE 802.3 AF standard.

Table 2: PoE Classes and Power Ratings

Class

Minimum Power Level Output from PoE Port

0

15.4 watts

1

4.0 watts

2

7.0 watts

3

15.4 watts

4

30.0 watts

Published: 2010-05-03