HP ProCurve zl Series User manual

Planning and
Implementation Guide
www.procurve.com
Power over Ethernet (PoE)
for zl and yl Products
PoE
Power over Ethernet Devices

ProCurve Power over Ethernet
(PoE) for zl and yl Products
Planning and Implementation Guide

© Copyright 2005 - 2007 Hewlett-Packard
Development Company, L.P. The information
contained herein is subject to change without notice.
This document contains proprietary information, which is
protected by copyright. No part of this document may be
photocopied, reproduced, or translation into another
language without the prior written consent of Hewlett-
Packard.
Publication Number
5991-6210
February 2007
Applicable Products
Disclaimer
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OF ANY KIND WITH REGARD TO THIS MATERIAL,
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Warranty
See the Customer Support/Warranty booklet included with
the product.
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Hewlett-Packard products and replacement parts can be
obtained from your HP Sales and Service Office or
authorized dealer.
ProCurve Switch 5406zl (J8697A)
ProCurve Switch 5406zl-48G (J8699A)
ProCurve Switch 5412zl (J8698A)
ProCurve Switch 5412zl-96G (J8700A)
ProCurve Switch 3500yl-24G-PWR (J8762A)
ProCurve Switch 3500yl-48G-PWR (J8693A)
ProCurve 620 Redundant and External
Power Supply
(J8696A)
ProCurve Switch zl Power Supply Shelf (J8714A)

iii
Contents
1 Introduction
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
Power Through the Cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
PoE Capabilities of the Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
Power Redundancy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
2 Operating Rules
Switch PoE Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
Provisioning Power for PoE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
Maximum PoE Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
PoE Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4
Switch Port Priority . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4
Switch Priority Class . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5
Line Loss . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5
PD Power Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
PD Power Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
3 Planning and Implementation for the Series 3500yl
Switches
Planning Your PoE Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
ProCurve 3500yl-24G-PWR Configuration . . . . . . . . . . . . . . . . . . . . . . . 3-2
ProCurve 3500yl-48G-PWR Configuration . . . . . . . . . . . . . . . . . . . . . . . 3-4
4 Planning and Implementation for the Series 5400zl Switch
Planning Your PoE Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
ProCurve 5406zl Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5
ProCurve 5406zl Configurations using the Power Supply Shelf 4-10
ProCurve 5412zl Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-11
Standard J8712A Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . 4-11
Standard J8713A Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . 4-15
Mixed J8712A and J8713A Configurations . . . . . . . . . . . . . . . . . . 4-18

iv
5 Infrastructure Requirements
Air conditioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
Power requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
Space . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2
Racks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2
Glossary
A Planning Considerations
General Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1
Specific Considerations for the 3500yl Switches . . . . . . . . . . . . . . . . . . . . A-2
Specific Considerations for the 5400zl Switches . . . . . . . . . . . . . . . . . . . . A-3
Index

1-1
Introduction
1
Introduction
This chapter provides an overview of Power over Ethernet (PoE) and a list of
reasons why you might want to implement PoE in your environment. It
discusses how PoE transmits power over twisted pair cable and the
capabilities of the devices used to provide PoE.
Overview
Power over Ethernet technology allows IP telephones, wireless LAN Access
Points and other appliances to receive power as well as data over existing LAN
cabling, without needing to modify the existing Ethernet infrastructure.
Power over Ethernet has become a standard feature of ethernet switches, as
the cost of adding power supplies to the Ethernet switches is small. IEEE
802.3af is an extension to the existing Ethernet standards. It offers the first
truly international standard for power distribution (consider how many
different AC power plugs exist worldwide).
Almost all appliances require both data connectivity and a power supply. Just
as telephones are powered from the telephone exchange through the same
twistedpair that carries the voice, we cannow do the same thing withEthernet
devices.
The technology is bound to make a big impact in the world of embedded
computing. In the realm of embedded computers, where the systems are
increasingly connected to LANs and the internet, the advantages of providing
power and data through a single cable should be obvious. Consider a typical
application: a system for a multi-level car parking garage that includes security
cameras, information signs, call-for-help telephones and vehicle sensors. Such
a system is distributed over a significant area, where main power is not easily
available. A single link to a PoE Ethernet Switch makes implementing this
system less expensive and faster than using a non-PoE switch.

1-2
Introduction
Overview
Introduction
Power over Ethernet connections to embedded computers will allow a less
expensive installation (no AC cabling, lower labor costs), facilitate updating
the installation and repositioning of end devices (wireless access points,
security cameras, and so forth) without electricians, while maintaining full
control over every node through the internet.
Figure 1-1 shows a typical system implemented to power telephones and
wireless access points. The PoE Ethernet switches are installed to supply
power over the twisted pair LAN cables to run phones or other appliances as
required.
Figure 1-1. Example of a Typical Implementation
5406zl Switch
3500yl-48G-PWR 3500yl-24G-PWR
Wireless
Access
Points
Cameras
Cameras
Phones
Phones
Mitel 3300
IP PBX
Wireless
Access
Points
620 RPS/EPS
Power Supply Shelf

1-3
Introduction
Overview
Introduction
Here are some reasons why you might want to do this:
■Simplifies installation and saves space - only one set of wires to bring to
your appliance.
■Saves time and money - there is no need to pay for additional electrical
power runs or to delay your installation schedule to make them.
■Minimal disruption to the workplace - the appliance can be easily moved,
to wherever you can lay a LAN cable.
■Safer - no AC voltages need to be added for additional network devices.
■As well as the data transfer to and from the appliance, you can use SNMP
network management infrastructure to monitor and control the
appliances.
■Appliances can be shut down or reset remotely - no need for a reset button
or power switch.
■When implementing wireless LAN systems it simplifies the radio
frequency (RF) survey task, as the access point can easily be moved and
wired in.
Power Through the Cable
A standard CAT5 Ethernet cable has four twisted pairs, but only two of these
pairs are used for 10Base-T and 100Base-TX data and all four are used for
1000Base-T data. The specification allows two options for using these cables
for power:
■The spare pairs are used. The pair on pins 4 and 5 are connected
together and form the positive supply, and the pair on pins 7 and 8 are
connected and form the negative supply.
■The data pairs are used. Since Ethernet pairs are transformer coupled
at each end, it is possible to apply DC power to the center tap of the
isolation transformer without upsetting the data transfer. In this mode of
operation the pair on pins 1 and 2 and the pair on pins 3 and 6 can be of
either polarity.
The standard does not allow both pairs (spare and data) to be used - a choice
must be made. The Power Sourcing Equipment (PSE) applies power to either
set of wires. ProCurve Networking switches, as a PSE, supply PoE power over
the “data pair” or, pins 1 and 2, and the pair on pins 3 and 6. The Powered
Device (PD) must be able to accept power from both options because mid-
span equipment must (according to the specification) supply power over the
“spare pair” or pins 4 and 5, and the pair on pins 7 and 8.
An obvious requirement of the specification is to prevent damage to existing
Ethernet equipment. A discovery process, run from the PSE, examines the
Ethernet cables, looking for devices that comply with the specification.

1-4
Introduction
Overview
Introduction
It does this by applying a small current-limited voltage to the cable and checks
for the presence of a 25k ohm resistor in the remote device. Only if the resistor
is present, will the full wattage be applied, but this is still current-limited to
prevent damage to cables and equipment in fault conditions.
The PD must continue to draw a minimum current. If it does not (for example,
when the device is unplugged) then the PSE removes the power and the
discovery process begins again.
PoE Capabilities of the Products
The ProCurve PoE switch devices are multiport switches that can be used to
build high-performance switched workgroup networks with PoE. These
switches are store-and-forward devices that offer low latency for high-speed
networking. The ProCurve PoE switch devices are designed to support
Redundant Power Supply and Power over Ethernet (PoE) technologies.
■The ProCurve Switch 3500yl-48G-PWR (J8693A), has 48 Integrated PoE
auto-sensing 10/100/1000Base-T RJ-45 ports with four dual-personality
Gigabit Uplink ports.
■The ProCurve Switch 3500yl-24G-PWR (J8692A), has 24 Integrated PoE
auto-sensing 10/100/1000Base-T RJ-45 ports with four dual-personality
Gigabit Uplink ports.
These switches also support somepre-standard PoE devices. For alist of these
devices, see the FAQs for your switch model. This feature is the default and
you must disable it if you do not want to use it. Refer to the Management and
Configuration Guide which is on the ProCurve Web site, www.procurve.com.
To display the list of downloadable manuals, click on the following links:
Technical support
Product manuals (all)
ProCurve Switch 3500yl or 6200yl Series.
(You may want to bookmark this Web page for easy access in the future.)