Ethernet Switches & Routers

How To-Brocade POE and POE+ Ready Campus Switches

by brcd-campus.expert on ‎01-19-2012 08:52 PM (4,187 Views)

BRCD-ENTERPRISE 2456

Introduction

Power over Ethernet (POE) and power over Ethernet Plus (POE+) are becoming Campus requirements for Education, Health, and the Financial World. Customers are demanding equal access, regardless of wired connection or wireless connection. This has led to network architects to look for switches that can deliver power over an Ethernet cable to run devices that require power to operate.  Vendors making edge devices that connect to the Campus are delivering products that can be powered from Ethernet Switches, thus eliminating running electrical circuits to areas where edge devices are installed. This technology gives the capability for edge devices to be placed in environments not possible in the past. Security Cameras, Wireless Access Points, Voice over IP phones, and environmental monitoring devices can be installed in environments that at one time running an electrical cable was not feasible.
This document discusses the POE Technology and identifies some of the Brocade Campus switches that support both POE and POE+.

Before You Begin

PoE and PoE+

The PoE standard defines power classes for up to a maximum of 15.4 watts (W) of power at the PSE ports. The actual PD gets about 12.95W of power after power dissipation (loss) over the copper wire. This is in compliance with safety standards and existing wiring limitations. Though limited by the 802.3af standard, 15.4W of power is ample, as most powered devices consume an average of 5 to 12W. IP phones, wireless LAN access points, and network surveillance cameras each consume an average of 3.5 to 9W. An off-the-shelf PD should belong to one of the classes defined by the PoE standard shown in Table 1.

Table 1: IEEE 802.3af PoE Standard Classes

StandardPoE ClassUsageMax Power (W) at PDMin Power (W) at PSE
802.3af0Default15.40.44-2.95
802.3af1Optional40.44-3.84
802.3af2Optional73.84-6.49
802.3af3Optional15.46.49-12.95

The IEEE 802.3at PoE+ (also called High Power) standard doubles the power at the PSE ports to a maximum of 30W, with the PD actually getting about 25.95W. The PoE+ standard is defined in anticipation of a next-generation class of PDs, which may require higher power than 15.4W. Existing examples of these PDs are 802.11n Wireless Access Points (APs). When high-power outdoor antennas are used over longer distance, 802.11n APs may demand more power from the PSE than the regular PoE can supply. An ordinary PoE-only switch may decline such a request and the PD may not function properly. A PoE+-capable PSE, such as the Brocade FastIron CX switches, can easily accommodate such power requirements, enabling next-generation IP endpoints and future proofing networks for applications to come. As more advanced PDs such as video IP phones and pan-tilt-zoom cameras are deployed in more media-rich campus environments, the full potential of PoE+ will be exercised.

The new PoE+ standard is a superset of the legacy PoE standard, so switches supporting PoE+ by default support legacy PoE capability as well. This is accomplished by bundling legacy PoE classes 0 through 3 (Type 1) and using the unused class 4 for high power (Type 2). Table 2 shows Table 1 from the PoE+ standard point of view. Table 3 compares the two standards side by side.

Table 2: 802.3at PoE+ Standards

StandardPoE ClassUsageMax Power (W) at PDMin Power (W) at PSE
802.3af (Type 1)0Default15.40.44-2.95
802.3af (Type 1)1Optional40.44-3.84
802.3af (Type 1)2Optional73.84-6.49
802.3af (Type 1)3Optional15.46.49-12.95
802.3af (Type 2)4Optional3012.95-25.5

Table 3: IEEE 802.3af PoE and 802.3at PoE+ side by side

Feature802.3af PoE802.3at PoE+
Cable RequirementCategory 3 or Category 5

Type 1: Category 3

Type 2: Category5/5E

PSE Current (A)0.35

Type 1: 0.35

Type 2: 0.60

PSE Voltage (Vdc)44-57

Type 1: 44-57

Type 2: 2.50-57

PD Current (A)0.35

Type 1: 0.35

Type 2: 0.60

PD Voltage (Vdc)37-57

Type 1: 37-57

Type 2: 47-57

Maximum PD Wattage (W)

Class 0, 3: 12.95

Class 1: 3.84

Class 2: 6.49

Class 4: Unused

Type 1: Class 0, 3: 12.95

Class 1: 3.84

Class 2: 6.49

Type 2: Class 4: 25.5

PD Classification Requirement

Optional

1-Event Classification

Required

Type1: 1-Event Classification

Type 2: 2-Event Classification and LLDP

Topic of Discussion


Deploying Brocade PoE-Based Solutions

Getting Ready for PoE

Before you can deploy PoE, it is important to calculate the power budget and to carefully plan the environment. A good starting point is to calculate the total number of end devices (PDs) that need to be powered up by a Brocade switch (PSE) and divide them by the power class to which they belong. All end devices, such as IP phones, access points, and cameras can be treated the same way with regards to PoE. Table 4 is an example of how to calculate power consumption.

Table 4: Power Budget Calculation

SwitchClass-1 PD (4W)Class-2 PD (7W)Class-3 PD (15.4W)Class-4 PD (30W)Total

First Floor Access

0W10-70W5-77W1-30W177W
Second Floor Access0W55-385W80-432W0-0W817W

Creating a table like in Table 4 helps you prepare you for the total power requirements and the circuit planning for the site. It is recommended that you talk to your Brocade representative (www.brocade.com)  for access to a Power Calculator tool for precise power requirements calculations.

Brocade FastIron CX Series PoE and PoE+ Switch

The 24-port FastIron CX supplies full Class 3 (15.4W) or full PoE+ (30W) of power to every port. The 48-port FastIron CX supplies full Class 3 power to every port, full PoE+ power to 26 ports, or a combination of the two staying within the switches 820W power budget.

Brocade ICX Series PoE and PoE+ Switch

The ICX Series Switches support the Power over Ethernet (PoE+) standard (802.3at) to provide up to 30 watts of power to each device. This high-powered solution simplifies wiring for next-generation edge devices, such as video conferencing and Voice over IP (VoIP) phones, pan/tilt surveillance cameras, and 802.11n wireless Access Points (APs). The PoE capability reduces the number of power receptacles and power adapters while increasing reliability and wiring flexibility. With a 1500-watt power budget per switch (with two power supplies), the Brocade ICX 6610 24-port and 48-port PoE models can supply up to Class 4 PoE+ (30 watts) power to every port.

PoE Scheduled Shutdown

The Brocade FastIron family of PoE switches can be configured to turn the PoE in-line power on specified ports on or off through Brocade IronView Network Manager (INM) management software. This feature is extremely useful to turn off the PoE power during non-business hours, weekends and holidays, reducing operating costs.

PoE Power Isolation

The Brocade FastIron modular products feature a unique power distribution design for the system and PoE power. Chassis are designed with independent system and PoE power subsystems. This design achieves optimal power operation and configuration, reducing equipment and ongoing costs compared to modular systems that use a common power supply for both systems and the PoE equipment. In the FastIron modular family, the power consumption of a line module’s PoE circuitry does not impact the system power. Similarly, the power consumption of the line modules, switch modules, and management modules does not impact the PoE power. Power consumption for the system and PoE are calculated, provisioned, and managed independently of one another. As more PDs are added, a simple power budget calculation determines whether another PoE power supply needs to be added to the switch. The system power distribution and the PoE power distribution subsystems are each designed for M+N load-sharing operation on the modular products. This dual-distribution power design simplifies the power configuration of the system while enhancing system reliability.

Related Information

For more information on Brocade PoE and PoE+ capable products, please visit www.brocade.com or talk to your local Brocade Account Team or Channel Partners.

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