Legacy PoE devices HP 5k series switches

[FreddyVC]

Ask: How to identify Legacy PoE PSE prior to disabling 

Explanation of ask:

We have a unique issue where some newer IEEE compliant PoE devices are creating high node trap counts. The solution received from another forum post suggests shutting off the legacy poe devices with the following commands. 

undo poe legacy enable pse 4 (based on number of switches) 
undo poe legacy enable pse 7
undo poe legacy enable pse 10
undo poe legacy enable pse 13
undo poe legacy enable pse 16
undo poe legacy enable pse 19

This works very well. We have not received the issues since; however, now we need to apply this to our entire organization which is thousands of switches. We DO have old equipment that may use Legacy PoE for PSE. What I need to do is prior to running the above commands, identify any Legacy PoE equipment that could be adversely affected by a change shutting off legacy settings. 

Any assistance would be very greatly appreciated! 

[Ivan_B]

Hi @FreddyVC !

Just to be sure I understand your question - are you looking for a Comware command that can show you if a PoE device connected to a particular switchport is 802.3af-compliant or pre-standard (so called 'inline power') compliant?

[FreddyVC]

Hello, 

        That's correct. We don't want to shut off legacy PoE on any of our switches without first knowing if a device requires that setting on. Here is an example of a pull from a 5500 I recently performed the change on. I performed the below before and after the change to see if any devices receiving power were then disabled. Management thought it best to detect these devices prior to the change...and I agree. I tried to space it out below so it was easy to read. Hopefully it comes across well in this post. 

<switchExample>dis poe int | in on
Interface    Status    Priority    CurPower     Operating     IEEE      Detection
GE1/0/1    enabled     low        3.8                 on                  2            delivering-power
GE1/0/22  enabled    low        6.2                  on                 4            delivering-power

[Ivan_B · Accepted solution]

That's a really smart approach and it makes a lot of sense in a production environment, I totally agree. But at the same time it's a tricky task if we speak about Comware's display commands available. I have checked relevant command's output, like 'display poe pse <PSE_number> interface' and 'display poe interface <port_number>' and none of these has a clearly defined field that could distinguish legacy prestandard devices from IEEE compliant ones.

There is one hint though - legacy devices should not report IEEE class. Thus, if you see a port where Operating Status is on, but IEEE Class is 0 it is a device that is unclassified and thus a potential suspect - a legacy device. It's not 100% reliable way, as there are not-very-compliant, but still partially IEEE-compliant devices that fail to report their class to the switch, but that can work without 'poe legacy enable'.  However at least you can narrow down thousands of devices to a much smaller list of 'suspects' and then check each device's specification to find out if it's compatible with IEEE 802.3af or not.

Unfortunately, I can't figure out any smarter way to achieve your target, let's see if somebody could recommend a better approach...