Cisco POE Switch Power draw on UPS

[luis@apptech.co.za]

Good day. 

I am in need of some advice. One of my clients have a Cisco Switch WS-C3750X-48P, and it seems the Power Supply is a removable unit.

When we connect this POE Switch onto a UPS, it fluctuates wildly on the power drain of the UPS. Connecting it to another UPS, it just downright forces the UPS to go into bypass mode.

My question is this: Is the switch faulty somehow, and if it is, is it the power supply, or the switch itself?

[Mark Malone]

Hi

Check the show env power  or show env when its connected up ? is it showing any power alerts in show logs too? is the UPS able to handle the load of the power supply's and all poe devices  ?

if switch is working fine when its connected to mains it could be something to do with the UPS your using

You can run the hardware through the Cisco cli analyzer online to check for general hardware issues, you can download it off the Cisco website

[luis@apptech.co.za]

Thank you for the response. 

No errors from the switch side regarding checking env power. UPS is definitely strong enough.

Symptoms only appear when we connect a POE device on the switch. Connecting only one device, an ip phone, and it starts the behavior. 

I will try the analyzing software and check what it reports

[Mark Malone]

what version of ios is switch running on

what type of ip phones are they , does same thing happen with non poe devices ?

might be software related issue worthy changing code as a test if its not in production yet ,

[luis@apptech.co.za]

Sorry, took me a while, needed to get the info from client, but they seem to be running on ios 12.5.

Seems the latest is 15?

Is there any specific upgrade path, or can i just jump to 15 straight without losing config?

IP Phones vary in make and model, but the same does not happen if non poe devices are plugged in.

The moment we plug in a POE device, the behaviour start. this can be a single ip phone, or one of the wi-Fi AP they have, doesn't matter.

[Mark Malone]

You can jump to 15 but you should always diff the config before and after with a software tool to make sure just in case some feature is not there but generally on 3750 you should be fine as there just campus switches , never heard of 12.5 on 3750 but if your going to 15 the recommended image is currently 15.0.2.SE11

if the software doesn't fix it you may have a faulty POE block on the board itself and it would then need to be RMA and replaced

[luis@apptech.co.za · Accepted solution]

Just wanted to thank you for all the help.

We had a situation with some power outages at the site, and then the switch went into a reboot cycle (just keeps rebooting). After a while, and powering of an on, etc, we got the switch up and running again, and after that, it actually plays nice with the UPS.

No abnormal behavior. I have no idea why this is, but it is working.