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POE not working on 1 port on WS-X4548-RJ45V+

Hi Experts,

Issue: POE is not working on 1 port in one module.


Background: We have CISCO 4507 switch running with "redundant mode" power supply. Have enough power supply to support POE. But facing issues with POE on 1 port in 1 module (WS-X4548-RJ45V+). However, data (internet) is working fine on this port and only PoE is not happening i.e. CISCO IP phone is not working. I checked by changing the CISCO IP phone (working one) but issue is same.


Switch is running on IOS version Version 12.2(54)SG1

Total inline power used is just under 1600 out of 4800 (available). See below:-


Power Summary Maximum
(in Watts) Used Available
---------------------- ---- ---------
System Power (12V) 550 2200
Inline Power (-50V) 1574 4800
Backplane Power (3.3V) 40 40
---------------------- ---- ---------
Total 2164 (not to exceed Total Maximum Available = 6000)


When I connect CISCO phone on other port on the same module then POE is working fine i.e. when connected to port 8 no POE but when connected to port 32 then getting POE.

No cabling issues as I used the same cable directly connected on the switch on these 2 switch ports.

No logs observed in the switch when CISCO phone is connected on problematic port.

In "show power inline" all interfaces are configured to "auto.

On this module 34 ports are being used out of 48 i.e.31 IP phones and 3 AP's. Total consuming about 450 watt power from PS.


Any thoughts?

I am not sure if its related to POE per ASIC or POE per module that we can get etc? I don't think this is the case because we can provide POE to any number of devices in each module if we have enough PS to support it.

Leo Laohoo
VIP Community Legend

Try this:
1. Command: test cable tdr interface G1/1;
2. Wait for approximately 61 seconds;
3. Command: sh cable tdr interface G1/1; and
4. Post the complete output to #3.

Hi Leo Laohoo - Thanks for your reply. Please see below required output:


sh cable tdr interface GiX/X 
Interface Speed Local pair Cable length Remote channel Status
GiX/X 0Mbps 1-2 N/A Unknown Terminated
3-6 N/A Unknown Terminated
4-5 N/A Unknown Terminated
7-8 N/A Unknown Terminated

Leo Laohoo
VIP Community Legend

Maybe PoE is turned off on the interface?

No. It is configured to Auto. See below:


sh power inline GiX/X
Available:4800(w) Used:1574(w) Remaining:3226(w)

Interface Admin Oper Power(Watts) Device Class
From PS To Device
--------- ------ ---------- ---------- ---------- ------------------- -----

Gi6/8 auto off 0.0 0.0 n/a n/a

Interface AdminPowerMax AdminConsumption
(Watts) (Watts)
---------- --------------- --------------------

GiX/X 30.0 15.4

Leo Laohoo
VIP Community Legend

It could be an IOS bug.
Try re-seating the line card. Keep an eye out for the log entries during re-seat.