HP ProCurve 1600M User manual

HP ProCurve
www.hp.com/go/hpprocurve
Po E
Power over Ethernet Devices
PoE Planning and
Implementation Guide

HP ProCurve
PoE Planning and
Implementation Guide

© Copyright 2004 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
5990-8801
August 2004
Applicable Products
Trademark Credits
Windows NT®, Windows®, and MS Windows® are US
registered trademarks of Microsoft Corporation.
Disclaimer
HEWLETT-PACKARD COMPANY MAKES NO WARRANTY
OF ANY KIND WITH REGARD TO THIS MATERIAL,
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS
FOR A PARTICULAR PURPOSE. Hewlett-Packard shall not be
liable for errors contained herein or for incidental or consequential
damages in connection with the furnishing, performance, or use
of this material.
The only warranties for HP products and services are set forth in
the express warranty statements accompanying such products and
services. Nothing herein should be construed as constituting an
additional warranty. HP shall not be liable for technical or editorial
errors or omissions contained herein.
Hewlett-Packard assumes no responsibility for the use or
reliability of its software on equipment that is not furnished by
Hewlett-Packard.
Warranty
See the Customer Support/Warranty booklet included with the
product.
A copy of the specific warranty terms applicable to your Hewlett-
Packard products and replacement parts can be obtained from your
HP Sales and Service Office or authorized dealer.
HP ProCurve Switch 2626-PWR (J8164A)
HP ProCurve Switch 2650-PWR (J8165A)
HP ProCurve Switch xl PoE Module (J8161A)
HP ProCurve 600 Redundant and
External Power Supply (J8168A)
HP ProCurve 610 External Power Supply (J8169A)

i
Contents
1 Introduction
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
Power Through the Cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
PoE Capabilities of the Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
2 Operating Rules
HP 600 RPS/EPS and HP 610 EPS Operation . . . . . . . . . . . . . . . . . . . . . . . . 2-1
Redundant Switch Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
Operating Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
External Switch Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3
EPS Power Allocation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3
Maximum PoE Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4
PoE Power With and Without EPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4
Switch Port Priority . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5
Switch Priority Class . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
Line Loss . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
PD Power Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
3 Planning
Supported Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
PD Power Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
Number of PDs per Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2
Planning Your PoE Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2
HP ProCurve 2626-PWR Configurations . . . . . . . . . . . . . . . . . . . . . . . . 3-3
HP ProCurve 2650-PWR Configurations . . . . . . . . . . . . . . . . . . . . . . . . 3-5
HP ProCurve Switch xl PoE Module Configurations . . . . . . . . . . . . . . 3-9
Infrastructure Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-14

ii
Glossary
Index

1-1
Introduction
1
Introduction
This chapter provides an overview of Power over Ethernet (PoE) and a list of
reasons why a user might want to implement PoE in their environment. It
discusses how PoE transmits power over twisted pair cable and the capabili-
ties 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.
IEEE 802.3af is an extension to the existing Ethernet standards. Power Over
Ethernet is likely to become a standard feature of ethernet switches in a few
years, as the cost of adding power supplies to the Ethernet switches is going
to be small. It offers the first truly international standard for power distribu-
tion (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
twisted pair that carries the voice, we can now do the same thing with Ethernet
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 car park that includes security cameras, informa-
tion 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 much
cheaper installation (no AC cabling, lower labor costs), facilitate updating the
installation and repositioning of sensors without electricians, while main-
taining full control over every node through the Internet, with VoIP and
webcam telephony. Functionality can be changed by downloading new soft-
ware through the network.
Figure 1 shows a typical system implemented to power telephones. 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
Here are some reasons why you might want to do this:
■Only one set of wires to bring to your appliance - simplifies installation
and saves space.
■There is no need to pay for additional electrical power runs or to delay
your installation schedule to make them- saves time and money.
hp procurve
PoE
xl module
J8161A
xl
module
PoE
Link Mode
123456
PoE-Ready 10/100-TX Pots (1-24)  all po ts a e HP Auto-MDIX
13 14
20
19121110
9
8
7
15
21
16
22 23 24
17 18
Std PoE PoE EPS
Status
LED Mode
Mode
Link
hp procurve
PoE
xl module
J8161A
xl
module
PoE
Link Mode
123456
PoE-Ready 10/100-TX Pots (1-24)  all po ts a e HP Auto-MDIX
13 14
20
19121110
9
8
7
15
21
16
22 23 24
17 18
Std PoE PoE EPS
Status
LED Mode
Mode
Link
hp procurve
PoE
xl module
J8161A
xl
module
PoE
Link Mode
123456
PoE-Ready 10/100-TX Pots (1-24)  all po ts a e HP Auto-MDIX
13 14
20
19121110
9
8
7
15
21
16
22 23 24
17 18
Std PoE PoE EPS
Status
LED Mode
Mode
Link
hp procurve
PoE
xl module
J8161A
xl
module
PoE
Link Mode
123456
PoE-Ready 10/100-TX Pots (1-24)  all po ts a e HP Auto-MDIX
13 14
20
19121110
9
8
7
15
21
16
22 23 24
17 18
Std PoE PoE EPS
Status
LED Mode
Mode
Link
HP 610
HP 5300xl
Mitel 3300
IP PBX
HP PoE Switch
HP PoE Switch
HP 600

1-3
Introduction
Overview
Introduction
■The appliance can be easily moved, to wherever you can lay a LAN cable
- minimal disruption to the workplace.
■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 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. 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 3 and 6 and the pair on pins 1 and 2 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. Hewlett-Packard has chosen to supply PoE power over the data
pair. The Powered Device (PD) must be able to accept power from both
options.
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. 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 Powered Device 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.

1-4
Introduction
Overview
Introduction
PoE Capabilities of the Products
The HP 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 offers low latency for high-speed
networking. The HP ProCurve PoE switch devices are designed to support
Redundant Power Supply and Power over Ethernet (PoE) technologies.
The 2650-PWR (J8165A) and 2626-PWR (J8164A) switches have 48 and 24 auto-
sensing 10/100Base-TX RJ-45 ports, respectively, and two dual-personality
ports—either auto-sensing 10/100/1000Base-T RJ-45, or mini-GBIC. The dual-
personality ports do not support PoE.
The HP ProCurve Switch xl PoE Module (J8161A) is a module for the HP
ProCurve 5300 xl Switch and has 24 auto-sensing 10/100-TX RJ-45 ports. All
24 ports are capable of supplying PoE power. However, for the module itself
to be able to supply PoE power it first must be connected to an EPS port on
an HP ProCurve 600 Redundant and External Power Supply (J8168A), or the
HP ProCurve 610 External Power Supply (J8169A), hereafter referred to as
the HP 600 RPS/EPS or the HP 610 EPS, respectively.
The Switch 2600-PWR Series devices can be connected to an HP 600 RPS/EPS
and receive full redundant power from the RPS part of the unit for switch
operation, if the internal power supply in the switch fails. If multiple switches
are connected to the RPS ports and several switches lose power at the same
time, the switch attached to the lowest RPS port number receives power. The
HP 600 RPS/EPS unit can provide all the power necessary to keep the switch
running.
EPS power from the HP 600 RPS/EPS is the PoE capability of the device and
supplies backup and additional power for the ports of the 2626-PWR,
2650-PWR switch devices. It also provides PoE power to the HP ProCurve
Switch xl PoE Module.
The HP 610 EPS can also be used for this purpose, to supply PoE power only.
The HP 610 EPS cannot supply RPS power, it can only supply PoE power.
These switch devices are designed to be used primarily as high-density wiring
closet or desktop switches. With these switches you can directly connect
computers, printers, and servers to provide dedicated bandwidth to those
devices, and you can build a switched network infrastructure by connecting
the switch to hubs, other switches, or routers. In addition, they support the
PoE standard, IEEE 802.3af, and can supply power over a twisted-pair cable
to power devices such as telephones and wireless access points.

2-1
Operating Rules
2
Operating Rules
This chapter discusses the operating rules and characteristics of PoE and
describes the capabilities of two devices. One is used to provide redundant
and external PoE power, the HP ProCurve 600 Redundant and External Power
Supply (J8168A), hereafter referred to as the HP 600 RPS/EPS, and the second
is used to provide external PoE power only., the HP ProCurve 610 External
Power Supply (8169A), hereafter referred to as the HP 610 EPS.
The HP 600 RPS/EPS and the HP 610 EPS are accessory products for the
Switch 2600-PWR Series devices, the HP ProCurve Switch xl PoE Module, and
specific other HP ProCurve switches. The redundant power supply (RPS) and
external power supply (EPS) features are explained below.
HP 600 RPS/EPS and HP 610 EPS
Operation
The HP 600 RPS/EPS monitors the power signal from a switch by detecting
that it is connected to the switch with an RPS or EPS cable. When the power
from the switch is no longer detected, the HP 600 RPS/EPS provides power to
the switch within 1 millisecond.
The HP 600 RPS/EPS supports hot plugging of an RPS or EPS cable. For more
information refer to the documentation that came with the HP 600 RPS/EPS.
For connectivity refer to the HP ProCurve Switch 2600 and 2600-PWR Series
Installation and Getting Started Guide that came with your switch.
The HP 610 EPS operates in much the same way except it does not supply
redundant, RPS power. It only has the capability to supply external PoE power.
Therefore, there are no RPS cables or ports on an HP 610 EPS.

2-2
Operating Rules
Redundant Switch Power
Operating Rules
Redundant Switch Power
The HP 600 RPS/EPS provides redundant power to any one of up to six switch
products, to back up the power supply in a switch in case of loss of AC power,
or a fault condition. The HP 600 RPS/EPS is an unmanaged power supply that
only provides information by way of LEDs or through the port interfaces to
attached devices.
Operating Characteristics
The HP 600 RPS/EPS has six RPS ports, each of which can provide redundant
+12V power to a connected switch, but only one port can provide this power
at a given time. If a switch with no AC power is connected to an operating HP
600 RPS/EPS, it will receive power if power is available (no higher priority
port is already using the RPS power).
Figure 2-1. Example RPS Connections on the HP 600 RPS/EPS

2-3
Operating Rules
External Switch Power
Operating Rules
If the power to a switch fails, power is provided from the HP 600 RPS/EPS, if
it is available, that is, if the HP 600 RPS/EPS is not already providing power to
a higher priority switch. If two or more devices fail, priority goes to the device
plugged into the lower numbered port on the HP 600 RPS/EPS unit. Conse-
quently the most important switch should be plugged into port one on the HP
600 RPS/EPS. In this state, the “Connected” LED should be ON, and the “Power
Status” LED should be BLINKING on the lower priority RPS port not supplying
power. (For further information refer to the Installation and Getting Started
Guide that came with your HP 600 RPS/EPS unit.)
External Switch Power
The HP 600 RPS/EPS provides external PoE power to up to two switch devices
through two EPS ports, and the HP 610 EPS provides external PoE power to
up to four switch devices through four EPS ports. The amount of PoE power
provided depends on how many switches (one to four) are connected. For
example, using an HP 600 RPS/EPS you can connect one EPS port to a Switch
2650-PWR and connect the other EPS port to an HP ProCurve Switch xl PoE
Module. Or, using an HP 610 EPS device you could connect up to four HP
ProCurve Switch xl PoE Modules, or any number of other variations.
EPS Power Allocation
The HP 600 RPS/EPS has one PoE power supply of 408 watts and the HP 610
EPS has two PoE power supplies of 408 watts each that can supply power to
connected switch devices either as the primary source of PoE power, such as
with the Switch xl PoE Module, or as a level of additional PoE power for
devices that have internal PoE power supplies. For the Switch 2626-PWR the
external PoE power is redundant power, used if the internal PoE power supply
fails. However, when both ports of pair A or pair B of the HP 610 EPS, or the
two ports of the HP 600 RPS/EPS are connected to two switches, the supplied
PoE power to each switch is cut in half. In other words, each switch only
receives 204 watts of PoE power.
The same holds true, for example, if you have connected one EPS port to a
Switch 2626-PWR and the other EPS port to an HP ProCurve Switch xl PoE
Module. The 408 watts from the HP 600 RPS/EPS will be split between the two
switch devices. However, if you are using an HP 610 EPS and you connect one
port of pair A to a Switch 2626-PWR and one port of pair B to an HP ProCurve
Switch xl PoE Module, they each will receive 408 watts.

2-4
Operating Rules
External Switch Power
Operating Rules
Maximum PoE Power
The Switch 2626-PWR provisions (allocates power to) ports 1-24 with 406
watts of power for PoE applications compatible with the IEEE 802.3af stan-
dard. The Switch 2650-PWR provisions ports 1-48 with 406 watts. This reduces
the per port wattage by half as compared to the Switch 2626-PWR.
However, by connecting an HP 600 RPS/EPS or an HP 610 EPS, you can
optionally provision ports 25-48 with 408 watts of external PoE power, thereby
bringing the per port wattage up to 15.4 watts per port, unless you have the
other EPS port of the HP 600 RPS/EPS or the other port of a pair on the HP
610 EPS connected to an HP ProCurve PoE device. In this case you cannot
provision the full 408 watts to the Switch 2650-PWR, only half, 204 watts.
Table 2-1. Maximum Power Allocations
PoE Power With and Without EPS
It is important to understand the PoE power requirements of these switch
devices because if the PoE power is not planned and implemented correctly,
end devices connected to the PoE switch ports may not receive power if an
internal switch PoE power source failure occurs.
PoE Power
Sources
PoE for Switch 2626-PWR PoE for Switch 2650-PWR HP ProCurve Switch xl
PoE Module
Internal
Only
406 watts available to ports
1-24.
406 watts available to ports 1-48. No internal PoE power.
Internal
and EPS
redundant 408/204* watts
available to ports 1-24. Only if
the internal power supply
fails.
406 watts available to ports 1-24
(provided by the internal source).
408/204* watts available to ports
25-48 (provided by the EPS source).
408/204* watts available to ports
1-24 from the EPS only.
EPS Only 408/204* watts available to
ports 1-24. (The EPS provides
PoE power to ports 1-24 only
if the internal power supply
fails.)
The internal power supply has
failed, and the EPS provides 408/
204* watts to ports 1-48. Note that
38 watts of this power are always
allocated exclusively to ports 1-24
or 25-48.) See page 3-5.
408/204* watts available to ports
1-24.
* If both EPS ports on the HP 600 RPS/EPS or both ports of a pair on the HP 610
EPS are connected to switches, each switch can receive 204 watts of power. If
a single switch is connected to the EPS ports, that switch can receive 408 watts.

2-5
Operating Rules
External Switch Power
Operating Rules
The Switch 2626-PWR has 24 ports and its internal PoE power supply provides
406 watts across all 24 ports. If an HP 600 RPS/EPS or an HP 610 EPS device
is connected to the Switch 2626-PWR for the purpose of supplying external
power to the PoE portion of the switch, there will be either 408 watts or 204
watts of power available should the switch’s internal PoE power supply fail.
If a single switch is connected to the EPS ports on the HP 600 RPS/EPS or a
single port of a pair on the HP 610 EPS, 408 watts are available, providing fully
redundant PoE power to the switch. If two switch devices are connected to
the EPS ports on the HP 600 RPS/EPS or to both ports of a pair on the HP 610
EPS, only 204 watts are provided to the switch if the internal PoE power supply
fails.
The Switch 2650-PWR PoE power requirements are different. This switch has
48 ports and the internal PoE power supply supplies 406 watts across all 48
ports. The switch reserves 38 watts for either ports 1-24 or 25-48, so that
neither set of ports receives the entire 406 watts.
By connecting an HP 600 RPS/EPS or an HP 610 EPS to the Switch 2650-PWR,
more PoE power is provided to the switch. With the HP 600 RPS/EPS or the
HP 610 EPS connected to the Switch 2650-PWR, the internal PoE power supply
provides the first 24 ports (1-24) with 406 watts and the HP 600 RPS/EPS or
the HP 610 EPS supplies the second 24 ports (25-48) with 408 or 204 watts (408
watts if only one switch is connected to the EPS ports; 204 watts if two
switches are connected to the EPS ports).
If the internal PoE power supply in the 2650-PWR switch fails, 408 watts or
204 watts are provided to ports 1-48. 38 watts of power are always allocated
to ports 1-25 or 25-48. See page 3-5.
Switch Port Priority
The lower the port number the higher the priority given. For example, port
number one has a higher priority than port number two. Therefore when both
ports need power, port number one is given power priority over port number
two and so on throughout the rest of the ports.
A port can be assigned a power priority that alters the assignment of power
to it by the switch. See the software manual that came with your switch for
details.

2-6
Operating Rules
External Switch Power
Operating Rules
Switch Priority Class
Port priority classification can be used by the switch to allocate power to
ports. It is a prioritization scheme by which the user can assign a low (default),
high, or critical priority to any given port. This assignment is done through
the command line interface (see the software manual that came with your
switch) of the switch and alters the hardware port-number priority for power
allocation.
■Low - Default. This priority class receives power only if all other priority
classes are receiving power. If there is enough power to provision PDs on
only some of the ports with a low priority, then power is allocated to the
ports in ascending order, beginning with the lowest-numbered port in the
class until all available power is in use.
■High - This priority class receives power only if all PDs on ports assigned
with a critical priority are receiving full power. If there is not enough
power to provision PDs on ports assigned with a “High” priority, then no
power goes to the low priority ports. If there is enough power to provision
PDs on only some of the “High” priority ports, then power is allocated to
the “High” priority ports in ascending order, beginning with lowest-
numbered high priority port, until all available power is in use.
■Critical - This priority class always receives power. If there is not enough
power to provision PDs on all of the ports configured for this class, then
no power goes to “High or Low” priority ports. If there is enough power
to provision PDs on only some of the “Critical” ports, then power is
allocated to the “Critical” ports in ascending order, beginning with the
lowest-numbered port in the class.
Line Loss
A certain amount of power is consumed from the switch to the powered device
(typically less than 16% loss), which can be influenced by cable length, quality,
and other factors. The IEEE 802.3af specification has addressed loss of power
by providing more power than a powered device requires. As well, depending
upon the classification (Class 0-3) of the device, the switch will provide more
or less power to address the specific power needs of that end device.
PD Power Classification
A PD is classified based on the maximum power it draws across all input
voltages and operational modes. The most common class is 0, in which the
switch will allow a maximum draw of 15.4 watts per port. As an example, 15.4
watts - Power Loss (16%) = 12.95 watts. See table 2-2.

2-7
Operating Rules
External Switch Power
Operating Rules
Table 2-2. Power Usage
As you can see in the table, any 802.3af compliant PD will never require more
than 12.95 watts. The switch provides a minimum of 15.4 watts at the port in
order to guarantee enough power to run a device, after accounting for line loss.
Class Usage Minimum Power Levels
at Output of PSE
Range of Maximum
Power required by
the PD
0 Default 15.4 Watts 0.44 to 12.95 Watts
1 Optional 4.0 Watts 0.44 to 3.84 Watts
2 Optional 7.0 Watts 3.84 to 6.49 Watts
3 Optional 15.4 Watts 6.49 to 12.95 Watts

— This page is intentionally unused. —

3-1
Planning
3
Planning
This chapter discusses the planning process a user should follow to success-
fully implement a PoE switch. After understanding what PoE is and its
operating rules, the next step to implementation is planning. The following is
an example list of considerations during the planning phase:
■What devices will need PoE power?
■How much power will each device require?
■What if power is lost to the switch?
• Power for the switch to operate (AC power)
• Power for PoE devices
■Which devices to plug into which ports and with what priorities?
■Are the appliances to be powered by PoE power supported?
Supported Products
The HP ProCurve Switch 2600-PWR Series devices and the HP ProCurve
Switch xl PoE Module support any products that meet the IEEE 802.3af PoE
standard.
PD Power Requirements
When a PD is initially connected to a PoE port, a minimum of 15.4 watts of
available power is required to begin the power-up sequence. This 15.4 watts
is needed to determine the type of PD requesting power (see “PD Power
Classification” on page 2-6). Once the power classification is determined and
power is supplied, any power beyond the maximum power requirements for
that class of PD is available for use.
In the default switch configuration all PoE ports have a Low priority. If the
switch has less than 15.4 W of PoE power available, the switch transfers power
from lower-priority ports to higher-priority ports. See “Switch Priority Class”
on page 2-6 for information on the use PoE port priority classifications. Within
each priority class, a lower numbered port is supplied power before a higher
numbered port.

3-2
Planning
Planning Your PoE Configuration
Planning
Disconnecting a PD from a port causes the switch to stop providing power to
that port and makes that power available to other ports configured for PoE
operation.
Number of PDs per Switch
The number of PDs supported per switch depends on the power allocation
and how much power each PD uses and how much power is left. The following
examples show the power consumption in some typical configurations.
Planning Your PoE Configuration
This section assists you in building a reliable and, if required, redundant PoE
configuration. Using the following examples you can plan, build, and connect
your PoE devices quickly and easily.
There are three configurations: one for the HP ProCurve Switch 2626-PWR,
one for the HP ProCurve 2650-PWR, and one for the HP ProCurve Switch xl
PoE Module. Each shows a complete configuration including an optional HP
600 RPS/EPS or HP 610 EPS unit. A table shows the PoE power available to
connected PoE devices when using just the switch or when using the switch
and either the HP 600 RPS/EPS or HP 610 EPS unit. The tables show the
available power when the HP 600 RPS/EPS or HP 610 EPS unit is providing
PoE power to connected switch devices.
Once you have selected your specific configuration and the PoE power
provided, you then add up the maximum amount of power each of your IEEE
802.3af-compliant devices require (use maximum power in watts, usually
found on a product’s data sheet). Adjust this total maximum power figure by
adding 15% to account for possible line loss. This value must be less than the
maximum power available shown in the table for your configuration.
If you are planning to include redundant power in your configuration you need
to determine which PoE devices must receive redundant PoE power, then total
their power requirements as explained in the paragraph above. The maximum
power figure must be less than the maximum power available when the switch
is powered by the HP 600 RPS/EPS or the HP 610 EPS unit, taking into
consideration the number of switches the HP 600 RPS/EPS or HP 610 EPS unit
is powering.