JunOS : PoE devices suddenly losing power on Juniper EX4300-48p

By | August 3, 2019

If your Power over Ethernet (PoE) device(s) connected to an EX 4300-48p switch suddenly lose power unexpectedly after some time working just fine, you may be experiencing PoE controller software issue.

First of all, verify if you are not over your PoE power budget (this could be sometimes the case when you have a LOT of devices connected – this kind of situation occurs only if you have a lot of type 2 high powered PoE (IEEE 802.3at) devices connected to it) :

You should see a similar output like this :

You should look at the “Total PoE power consumed”. If you are equal or tight to the limit, it might be just your problem, you should disconnect a few devices/relocate them on another switch and see if there is any improvement.

In this particular situation, the output above was taken immediately after the “PoE outage” occurred. All devices were connected properly, but no power was injected by the switch and consumed by the devices. Down/Up the port(s) had no effect.

It then came to mind to have a look at the “PoE controller”

Here is an example of the output of this command :

As we can see, there is a notification that a new version of the PoE software is available. In my case, that was the issue, most likely a bug in the current version that I was running.

NOTE : It may be a good idea to validate first if you are running the recommended JunOS version by JTAC. If not, upgrading that first is recommended.

NOTICE : Before you continue, this upgrade need to be performed within a maintenance window, a minimum of 10 – 15 minutes will be required, as in addition of upgrading the PoE software, the switch will automatically reboot once completed. The switch may become unstable while performing the upgrade.

In order to perform the PoE software upgrade, do the following command :

NOTE : Please note that if you are running a virtual-chassis, the command will need to be performed for all unit and change the “fpc-slot” number matching the other units in the VC.

You will now notice the following output once you’ve issued the PoE firmware upgrade :

Once the switch(es) completed their upgrade and rebooted, the PoE injection should be stable and steady.

[This article may also apply to EX2200, EX3200, EX2300, EX3300, EX3400-p chassis as well]