The
max max-wattage
option for the Auto and Static states is used to restrict the use of higher power
Cisco PDs. This command should not be applied to Avaya or other vendor PDs. Be careful when using
this option because there are two reasons fixed switches will remove power from a port:
A PD requires more power than the Max option is set to provide
The Max option is set lower than the PoE class maximum value for a non-Cisco PD
You can detect if one of the two conditions listed above happens by using the
show power inline
command. If you see “
power-deny
” instead of “
on
”, in the oper column, either the PD requested too much
power or the max max-wattage value was lower than the IEEE class maximum value. You cannot use the
max max-wattage
option to save logical power to increase the number of PDs on a switch.
The Catalyst 3750 has a command to reclaim logical power for non-Cisco PDs beginning with IOS
12.2(25)SEC. This command sets a power ceiling that is more than the device will draw, but less than the
max value of the PoE class range. The command is
power inline consumption default
[
wattage value].
This command can be applied in “global configuration mode” for the entire switch or
individual values for each interface (port).
A global setting of 6 watts for every port would be:
Switch (config)# power inline consumption default 6000
An individual port setting for port 2 at 11 watts would be:
Switch (config)# interface gigabitethernet 1/0/2
Switch (config-if)# power inline consumption default 11000
This command is extremely useful if you are deploying non-Cisco class-3 PDs. The value is greatly
diminished when deploying class 2 or class 1 PDs because the difference between the actual power-draw
and the class maximum value is much smaller than with the class-3 range for IP telephones. Remember to
allocate enough power for a worst case PD power draw and to traverse 100 meters of cable. Table 2 can
help you decide how much additional power is needed to travel over 100 meters.
Catalyst 3560 and 3750 IOS Common Notes:
The “power inline” command was added to IOS 12.1(19)EA1
The “static” and “max” features were added to IOS 12.2(25)SE
Never use IOS earlier than 12.2(20)SE1 because power could still flow through a port even after the
valid PD was removed. This could damage a non-PD device.
Catalyst 3750 IOS Specific Note:
The “power inline consumption” feature was added to IOS 12.2(25)SEC
End of Fixed Switch section
MJK
Copyright ©
2006 Avaya Inc. All Rights Reserved.
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