Cisco Aironet 1300 Power Injector LR2 Datasheet

Cisco Aironet Power over Ethernet
Application Note
Introduction
The goals of this document include the following:
•
Identify Cisco inline-powered WLAN devices and their usage requirements with a Cisco
inline-powered switch, mid-span device, or injector-powered solution.
•
Help identify compatibility to enable the selection of the appropriate powered solution for the
deployed device.
•
Identify implementation requirements for all Cisco WLAN products that operate from inline power
via Cisco pre-standard power, IEEE 802.3af, and the emerging 802.3at standard.
Types of Power over Ethernet
This section describes various types of Power over Ethernet (PoE) including Cisco pre-standard power,
IEEE 802.3af power, and IEEE 802.3at power.
Cisco Pre-Standard Power
The first generation of Cisco pre-standard PoE was designed to power devices such as Cisco IP phones
and access points. This pre-standard solution had relatively low power requirements (approximately 6 to
7 watts). Later generations of pre-standard power supported higher power modes (up to 15 Watts) and
added power negotiation via Cisco Discovery Protocol (CDP). In July 2003, the IEEE ratified the
802.1af standard (up to 15.4 watts of power). With the ratification of IEEE 802.3af, Cisco supports both
IEEE 802.3af and Cisco pre-standard PoE concurrently. Cisco has also extended pre-standard power
management using CDP negotiation to Cisco IEEE 802.3af compliant devices to further optimize Power
Source Equipment (PSE) power management.
When using a Cisco pre-standard source for power, it is important to check the power draw in watts
(Table 1) and verify that the PSE can supply enough wattage to the powered device. Depending on the
version of your PSE, enough power may not be available to supply some of the newer access points.
Americas Headquarters:
Cisco Systems, Inc., 170 West Tasman Drive, San Jose, CA 95134-1706 USA
© 2007 Cisco Systems, Inc. All rights reserved.
Types of Power over Ethernet
REVIEW DRAFT—CISCO CONFIDENTIAL
IEEE 802.3af Power
The IEEE 802.af-2003 PoE standard:
Note
•
Defines terminology to describe a port that acts as a power source to a powered device.
•
Defines how a powered device is detected.
•
Defines two methods of delivering PoE to the discovered device requiring power.
•
End-Point PSE—PoE-capable Ethernet port. Power may be delivered by an end-point PSE to a
powered device using the active data wires of an Ethernet port or the spare wires. An end-point
PSE, such as a PoE-capable Ethernet switch may implement either scheme.
•
Mid-span PSE—Can be used to deliver PoE if an existing non-PoE-capable Ethernet switch is
used. If a mid-span PSE is used, it can only implement power delivery over the spare pairs of
the copper cabling and cannot be used to deliver PoE over 1000BASE-T connections.
Only one mechanism may be used at a time to deliver power to a powered device because the design of
the device.
Figure 1
End-Point PSE PoE Delivery
End-Point PSE Power
over Ethernet Delivery
232180
10/100/1000BaseT
Power delivery, supported within Cisco Catalyst Ethernet switches, relies on the data pairs (pins 1-2 and
3-6) to transmit power (sometimes referred to as “phantom” power). The second mechanism relies on
the unused data pairs (pins 4-5 and 7-8) to deliver power that is supported within mid-span power
delivery.
IEEE 802.3at Power
In September 2005, the IEEE began work on a higher power standard for PoE. This standard has not yet
been ratified. Unlike 802.3af (which has a limit of 15.4 watts and must work with the limitations of
Category 3 cable), IEEE twice the PoE power support (approximately 30 watts using two pairs).
Although still in discussion, the standard may include PoE power support as high as 60 watts (using four
pairs). The main purpose of 802.3at is to enable more power to operate over an Ethernet cable.
Additionally, the task force has agreed to allow gigabit mid-span products and has granted them the
ability to choose either active data pairs or spare pairs for the power delivery.
Cisco Aironet Power over Ethernet Application Note
2
PoE Requirements for Cisco Access Points
REVIEW DRAFT—CISCO CONFIDENTIAL
Note
A 1000BASE-T mid-span device is a product in the middle of the circuit that can provide power.
This product can be a powered Ethernet source, an injector, or other mechanism for inserting
PoE.
PoE Requirements for Cisco Access Points
To determine if a particular switch or PSE can supply enough power to an access point, the installer
needs to verify the amount of power the access point draws and confirm that there is enough power
present to operate it. Depending on the make, model, and radio configuration, the access point can draw
different amounts of power. Table 1 presents the power requirements (in watts) for Cisco Aironet access
points.
Table 1
Cisco Aironet Access Point Power Requirements (in watts)
Cisco Aironet Access Point
Access Point Input Power
PSE Output Power (considers
cable loss)***
350/BR350
5.750
6.000
521 with 802.11g radio (802.3af 9.900
compatible)
9.910
1000 with both 802.11a/g radios 6.700
(802.3af compatible)
6.750
1120 with 802.11b radio
4.750
4.900
1121 with 802.11g radio
4.750
4.900
1130 with 802.11g radio
(802.3af compatible)
9.900
9.910
1130 with 802.11a and 802.11g
radios (802.3af compatible)
11.10
12.20
1200 without installed radios
4.30
4.42
1200 with 802.11b radio
6.00
6.24
1200 with 802.11g radio
6.20
6.460
1200 with 802.11a (RM20) black 8.00
stripe paddle antenna
8.50
1200 with 802.11a (RM21)
white stripe paddle antenna (or
RM22)
9.50
10.14
1200 with 802.11a (RM20) and
802.11b radio
10.80
11.64
1200 with 802.11a (RM20) and
802.11g radio
10.20
10.95
1200 with 802.11a (RM21) and
802.11g radio
11.20
12.12
1200 with 802.11a (RM21) and
802.11g radio
11.40
12.36
Cisco Aironet Power over Ethernet Application Note
3
PoE Requirements for Cisco Access Points
REVIEW DRAFT—CISCO CONFIDENTIAL
Table 1
Cisco Aironet Access Point Power Requirements (in watts)
Cisco Aironet Access Point
Access Point Input Power
PSE Output Power (considers
cable loss)***
1240 with 802.11g radio
(802.3af compatible)
11.40
12.960
1240 with 802.11a and 802.11g
radios (802.3af compatible)
12.95
15.00
1250 without installed radios
9.00
9.00
1250 with a single radio either
802.11a/n or 802.11bg/n
12.95
15.4
1250 with both 802.11a/n and
802.11bg/n radios**
16.5
18.5
* 1250 with one radio: 802.3af compatible.
** 1250 with two radios: beginning late 2007, Cisco will enable auto-negotiating,
single-port power for the Cisco Aironet 1250 Access Point on leading switches
across the Catalyst portfolio.
*** PSE value in watts is the value the power device will use for CDP.
The figures used in Table 1 were calculated as described below in Figure 2.
Note
The power requested for the switch/box by the access point must take into account the resistance
of 100 m of Category 5 Ethernet cable.
Figure 2
Power Calculation Formula for PSE
V = voltage, R = resistance of cable (Ohms), PowerPD = power Consumed by the access point (W)
The worst case voltage is 40 V. The resistance of the Category 5 cabling is in Ohms.
Note
Always check the power specifications of the PSE (switch, mid-span power, or injector) to confirm that
it can support the access point you are deploying. If the PSE cannot supply enough power, the access
point radios may be disabled or the access point may repeatedly “reboot” as the device draws more power
than the PSE can supply. This imbalance trips the breaker causing it to reset as the breaker cools down
and causes the access point to appear to be cycling or rebooting.
Cisco Aironet Power over Ethernet Application Note
4
Using a Cisco Power Injector
REVIEW DRAFT—CISCO CONFIDENTIAL
Using a Cisco Power Injector
In environments with fewer installed access points, it may be more cost effective to use a Cisco Power
Injector. Table 2 is a guide to assist with selecting the correct power injector.
Table 2
Cisco Power Injectors and the Supported Access Points
Cisco Aironet Access Points
Power Injector
350-BR350 series* (old injector AIR-PWRINJ=) AIR-PWRINJ3
1000 series
AIR-PWRINJ-1000AF
1100/1120 series* (old injector AIR-PWRINJ2=) AIR-PWRINJ3
1130 series*
AIR-PWRINJ3
1200 series* (old injector AIR-PWRINJ1200=)
AIR-PWRINJ3
1240 series*
AIR-PWRINJ3
1250 series
AIR-PWRINJ4
BR1300 series
AIR-PWRINJ-BLR2=
BR1300 series (when operation from +12 VDC is AIR-PWRINJ-BLR2T=
desired)
BR1400 series
AIR-PWRINJ-BLR1=
1500 series
AIR-PWRINJ-1500=
1520 series
AIR-PWRINJ-1500-2=
* These units can also support the powered fiber
injector
AIR-PWRINJ-FIB=
Powering the Cisco Aironet 1250 Series Access Point in High
Power (18.5-Watt Mode)
Powering access points with additional features such as radio modules may cause the access point to
exceed 15.4 watts (the limits of 802.3af). There are several short-term ways to solve this problem.
Note
Only use ONE source of power at any time.
1.
Deploy using local power such as the Cisco Power Supply (AIR-PWR-SPLY1=)
2.
Deploy using a mid-span device such as a Cisco Power Injector (AIR-PWRINJ4=)
3.
Deploy on applicable Catalyst switches using Cisco Intelligent Power Management (See Figure 3).
Cisco Aironet Power over Ethernet Application Note
5
Powering the Cisco Aironet 1250 Series Access Point in High Power (18.5-Watt Mode)
REVIEW DRAFT—CISCO CONFIDENTIAL
Figure 3
Power from a Cisco Catalyst Switch Using Cisco Intelligent Power Management
.
Cisco Aironet
power injector
Cisco powered switch
232179
Local power
CCVP, the Cisco logo, and the Cisco Square Bridge logo are trademarks of Cisco Systems, Inc.; Changing the Way We Work, Live, Play, and Learn
is a service mark of Cisco Systems, Inc.; and Access Registrar, Aironet, BPX, Catalyst, CCDA, CCDP, CCIE, CCIP, CCNA, CCNP, CCSP, Cisco,
the Cisco Certified Internetwork Expert logo, Cisco IOS, Cisco Press, Cisco Systems, Cisco Systems Capital, the Cisco Systems logo, Cisco Unity,
Enterprise/Solver, EtherChannel, EtherFast, EtherSwitch, Fast Step, Follow Me Browsing, FormShare, GigaDrive, HomeLink, Internet Quotient,
IOS, iPhone, IP/TV, iQ Expertise, the iQ logo, iQ Net Readiness Scorecard, iQuick Study, LightStream, Linksys, MeetingPlace, MGX, Networking
Academy, Network Registrar, PIX, ProConnect, ScriptShare, SMARTnet, StackWise, The Fastest Way to Increase Your Internet Quotient, and
TransPath are registered trademarks of Cisco Systems, Inc. and/or its affiliates in the United States and certain other countries.
All other trademarks mentioned in this document or Website are the property of their respective owners. The use of the word partner does not imply
a partnership relationship between Cisco and any other company. (0709R)
© 2007 Cisco Systems, Inc. All rights reserved.
Cisco Aironet Power over Ethernet Application Note
6

* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project