how to use " show power inline" and interpret its output

Answered Question
Dec 26th, 2008

Hi every body!

I have few questions:

My book shows the command:

show power [type mod/num]

1) I don't understand the " [type mod/num]" part. Would someone please give me example?

My book shows:

switch# show power inline

module available used remaining

(watts) (watts)

1 370.0 39 331

question #2 Is" 370" the result of" 15.4*number of PoE ports" (total ports active and off inclusive) ?

thanks a lot!

I have this problem too.
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Correct Answer by Edison Ortiz about 7 years 11 months ago

Sarah,

The figure posted in your original post came from a non-modular switch - most likely a 3750/3560.

A power output from a modular switch would be different and the power supply will provide the power to the PoE modules are per their specs. Each PoE will have sufficient power to power all of its switchports when needed.

HTH,

__

Edison.

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Edison Ortiz Fri, 12/26/2008 - 17:52

Sarah,

The command option may be different depending on the hardware is used.

For available show power options, please refer to the 6500 documentation:

http://www.cisco.com/en/US/docs/ios/fundamentals/command/reference/cf_s2.html#wp1435153

Your second output looks closer to what you will find in a 3750 switch:

http://www.cisco.com/en/US/docs/switches/lan/catalyst3750/software/release/12.2_46_se/command/reference/cli2.html#wp9457661

370 Watts is what's available by the switch for PoE. Anything over 370 total consumption won't power up. If you have a 48 Port switch, you won't be able to power-up all phones at that wattage and that's why CDP is so important for managing phone power consumption.

HTH,

__

Edison.

sarahr202 Fri, 12/26/2008 - 18:58

Thanks for your reply Edison!

My understanding is first the supervisory module powers up first, if enough power available, then 2nd module from the top, if enough power is available then 3rd and so on.

After all modules powered up and then there is enough power available, the highest PoE port on 1st module is powered up, then 2nd highest PoE port and so on.

How did we get this 370 watts?

How does module decide it needs 370 watts?

(just to make my point, consider the module with 3 PoE ports)

How about a module with only 3 PoE ports, how much power can be allocated to such module considering enough wattage is available from the power supply?

thanks a lot!

viyuan700 Fri, 12/26/2008 - 19:46

How did we get this 370 watts?

How does module decide it needs 370 watts?

some of the power supply for 3750 switch. So this 370W is the power from power supply module only for PoE. This can supply 15.4W power to all 24 ports (370/24=15.4W). Similarly there is for 48 ports 740W.

• C3K-PWR-750WAC: 750WAC power supply for 24-port switch with 370W PoE

• C3K-PWR-265WAC: 265WAC power supply for 48-port or 24-port switch without PoE

How about a module with only 3 PoE ports, how much power can be allocated to such module considering enough wattage is available from the power supply?

Maybe applicable to a power supply that can not supply 15.4 W to all 24 ports .

Correct Answer
Edison Ortiz Sat, 12/27/2008 - 08:49

Sarah,

The figure posted in your original post came from a non-modular switch - most likely a 3750/3560.

A power output from a modular switch would be different and the power supply will provide the power to the PoE modules are per their specs. Each PoE will have sufficient power to power all of its switchports when needed.

HTH,

__

Edison.

viyuan700 Fri, 12/26/2008 - 18:28

i dont have command show power it has show power inline in Unified 500 series UC520

USA_HQ#sh power ?

inline Show inline power status

USA_HQ#sh power inline ?

FastEthernet FastEthernet IEEE 802.3

actual Show current power status

cards Show current cards power status

configured Show configured power status

| Output modifiers

Output for interface 0/1/7 means 8th interface to which IP phone is connected plus output of other commands

USA_HQ#sh power inline f0/1/7

PowerSupply SlotNum. Maximum Allocated Status

----------- -------- ------- --------- ------

INT-PS 0 80.000 10.250 PS GOOD

Interface Config Device Powered PowerAllocated

--------- ------ ------ ------- --------------

Fa0/1/7 auto IEEE-3 On 10.250 Watts

USA_HQ#sh power inline actual

Interface Power

-------------------- -----

Fa0/1/0 no

Fa0/1/1 no

Fa0/1/2 no

Fa0/1/3 no

Fa0/1/4 no

Fa0/1/5 no

Fa0/1/6 no

Fa0/1/7 yes (10.250 Watts)

USA_HQ#sh power inline cards

Card Desc. SlotNum. Config Maximum Allocated

----------- -------- ------ ------- ---------

0 123.200 10.250

USA_HQ#sh power inline configured

Interface Config

-------------------- ------

Fa0/1/0 auto

Fa0/1/1 auto

Fa0/1/2 auto

Fa0/1/3 auto

Fa0/1/4 auto

Fa0/1/5 auto

Fa0/1/6 auto

Fa0/1/7 auto

sarahr202 Fri, 12/26/2008 - 19:00

thanks for your reply!

Edison sent me a link which shows the use of

"Show power inline module 1"

thanks a lot!

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