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Catalyst 6500 Series Switch Software Configuration Guide—Release 8.7
OL-8978-02
Chapter 55 Configuring a VoIP Network
Configuring VoIP on a Switch
Available Power
Table 55-5 lists the available power that can be supplied for each port for the voice daughter cards.
For example, if the powered device requires 6.3 W, then the allotted power for that port using a daughter
card with 89 percent efficiency must be 6.3/(0.89) = 7 W. If you are using a voice daughter card with
100 percent efficiency, then the allotted power is 6.3 W.
Wall-Powered Phones
When a wall-powered phone is present on a switching module port, the switching module cannot detect
its presence. The supervisor engine discovers the phone through CDP messaging with the port. If the
phone supports the inline power (the supervisor engine determines this through CDP), and the mode is
set to Auto, Static, or Off, the supervisor engine does not attempt to power on the port. If a power outage
occurs, and the mode is set to Auto, the phone loses power, but the switching module discovers the phone
and informs the supervisor engine, which then applies the inline power to the phone. If a power outage
occurs, and the mode is set to Static, the phone loses power, but the switching module discovers the
phone and applies the preallocated inline power to the phone.
Powering Off the Phone
The supervisor engine can turn off power to a specific port by sending a message to the switching
module. The power for a port in Auto mode is then added back to the available system power. The power
for the ports in Static mode is not added back to the available system power. This situation occurs only
when you power off the phone through the CLI or SNMP.
Phone Removal
The switching module informs the supervisor engine if a powered phone is removed using a link-down
message. The supervisor engine then adds the allocated power for that port back to the available system
power.
In addition, the switching module informs the supervisor engine if an unpowered phone is removed.
Caution When a phone cable is plugged into a port and the power is turned on, the supervisor engine has a
4-second timeout waiting for the link to go up on the line. During those 4 seconds, if the phone cable is
unplugged and a network device is plugged in, the device could be damaged. We recommend that you
wait at least 10 seconds between unplugging a device and plugging in a new device.
Table 55-5 Efficiency of Voice Daughter Cards
Daughter Card
Maximum Power
Per Port (W) Efficiency
WS-F6K-PWR 6.3 100%
WS-F6K-VPWR-GE 6.3 89%
WS-F6K-GE48-AF 15 89%
WS-F6K-FE48-AF 15 89%
WS-F6K-FE96-AF 15 89%
