Cisco 3850 Short-circuit BISP Events on Log

[fdharmawan]

Hi Guys,

So couple days ago one of my switch unit on the stack suddenly shut down. I unplugged all the cables (stack power, stack data, and power supply). Then I boot up the switch with PSU only, no stack cable attached. After the switch finished booting up, I found the following command repeatedly shown in the console.

Nov 4 08:03:55.007 JKT: %PLATFORM_STACKPOWER-4-BISP_PORT_A_SC: Switch 2 experienced a short-circuit BISP event on port 1

Nov 4 08:04:56.825 JKT: %PLATFORM_STACKPOWER-4-BISP_PORT_A_SC: Switch 2 experienced a short-circuit BISP event on port 1
Nov 4 08:05:28.015 JKT: %PLATFORM_STACKPOWER-4-BISP_PORT_A_SC: Switch 2 experienced a short-circuit BISP event on port 1
Nov 4 08:06:00.691 JKT: %PLATFORM_STACKPOWER-4-BISP_PORT_A_SC: Switch 2 experienced a short-circuit BISP event on port 1

I thought it only affects the stack power unit, but when I plugged the IP phones and APs back, none of the ports are operational. I checked the log, I got the following message.

%ILPOWER-7-DETECT : Interface Te2/0/1: inline power denied. Reason : insufficient power

So I checked the power inline, and discovered it has no power supplied.

Module Available Used Remaining
(Watts) (Watts) (Watts)
------ --------- -------- ---------
2 n/a n/a n/a

While on the other unit, I got the power

Module Available Used Remaining
(Watts) (Watts) (Watts)
------ --------- -------- ---------
1 1440.0 187.4 1252.6

I tried to disable the stack-power port so I can suppress the alerts by issuing "stack-power switch 2 port 1 disable" command, but the alerts still there.

I read the following post https://community.cisco.com/t5/switching/cisco-3850-poe-switch-power-issue-with-ports/td-p/4138611 and the bug related https://bst.cloudapps.cisco.com/bugsearch/bug/CSCvj76259?rfs=iqvred. My current version is 16.3.7 and my unit is WS-C3850-24XU. So if I upgrade to 16.6.X and the issue still persists, does it mean the MOSFET is causing this? Is there any other way to confirm the issue? Thanks.

[guixian]

My site environment is two 3750-E stacks, version 12.2 (55) SE5, and also a short-circuit built-in self-protection (BISP) event. I tried to replace the power module once, but it still didn't solve the problem. Can you help me to explain under what circumstances the BISP event will occur and how to troubleshoot it?

[Leo Laohoo]

Create a new thread.

[Reza Sharifi]

Hi,

Maybe, you had a power brownout that affected that one switch.

HTH

[fdharmawan]

Hi Reza,

What is power brownout? May I know how to check it?

[Georg Pauwen]

Hello,

if you have a spare PSU (or just take one out of one of the other switches), replace the current one with the spare, and check if the PSU itself might be the problem.

By the way, a brownout is a drop in voltage, as opposed to a blackout, which is a complete loss of power.

[fdharmawan]

Hi Georg,

We might have a spare PSU from a faulty unit. May I know how to check the drop in the voltage? Is there any command that I should issue?

[marce1000]

 - FYI : https://bst.cloudapps.cisco.com/bugsearch/bug/CSCtj52215

 M.