C I S C O C O N F I D E N T I A L - D r a f t A 1
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Cisco Aironet 1250 Series Access Point Hardware Installation Guide
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Chapter 4 Troubleshooting 1250 Series Lightweight Access Points
Low Power Condition for Lightweight Access Points
On power up, the access point is placed into low power mode (both radios are disabled), Cisco IOS
software loads and runs, and power negotiation determines if sufficient power is available. If there is
sufficient power then the radios are turned on; otherwise, the access point remains in low power mode
with the radios disabled to prevent a possible over-current condition. In low power mode, the access
point activates the Status LED low power error indication (see the
“Checking the Lightweight Access
Point LEDs” section on page 4-3
Intelligent Power Management - need changes
The access point requires
xx W of powe
r ( needs
zz W of power
when operating in low power mode with
both radios disabled. To help avoid an over-current condition with low power sources and to optimize
power usage on Cisco switches, Cisco developed Intelligent Power Management, which uses Cisco
Discovery Protocol (CDP) to allow powered devices (such as your access point) to negotiate with a Cisco
switch for sufficient power.
The access point supports Intelligent Power Management and as a result of the power negotiations, the
access point will either enter full power mode or remain in low power mode with the radios disabled.
Note
Independent of the power negotiations, the access point hardware also uses the 802.3af classification
scheme to indicate the power required from the power source. However, the power source cannot report
the power available to the access point unless the power source also supports Intelligent Power
Management.
Some Cisco switches that are capable of supplying sufficient power require a software upgrade to
support Intelligent Power Management. If the software upgrade is not desired, you can configure the
access point to operate in pre-standard compatibility mode and the access point automatically enters full
power mode if these Cisco switches are detected in the received CDP ID field.
When the access point determines that sufficient power is not available for full power operation, an error
message is logged and the Status LED turns amber to indicate low power mode (see the
Lightweight Access Point LEDs” section on page 4-3
and the
“Inline Power Status Messages” section
Tip
If your switch is capable of supplying sufficient power for full operation but the access point remains in
low-power mode, your access point or your switch (or both) might be misconfigured (see
The access point can be powered by these options:
•
Use the 1250 series power injector (AIR-PWRINJ4) on the switch port
•
Use the 1250 series DC power module (AIR-PWR-SPLY1) to locally power the access point
Inline Power Status Messages
These messages are logged on the console port by the access point to report the power condition:
•
%CDP_PD-4-POWER_OK: Full Power - AC_ADAPTOR inline power source—This message
indicates the access point is using the power module and can support full-power operation.
•
%CDP_PD-4-POWER_OK: Full Power - NEGOTIATED inline power source—This message
indicates the access point is operating at full power and has successfully negotiated for 12.95 W of
power from a Cisco switch supporting Cisco Intelligent Power Management.
