Catalyst 9300L PoE Strangeness

[Willrockhopper]

I've recently deployed a handful of Catalyst 9300L's and they're having some odd PoE issues which I've not seen on any of our MS switches. Firstly, the switches are denying PoE to new devices when total PoE consumption is at only 14% and total budget is at 50%.

Secondly, the switches are only giving devices a fraction of the power they're requesting, even when giving them full power would not exceed (or come close to) budget. For example, a range of high end security cameras requesting 30W are only being allocated around 6W or less by the switch.

I should note that we are managing these with Meraki dashboard and they are currently on CS 17.1.4

Maybe this is normal behaviour and I'm just not educated enough on using Catalyst switches via Meraki, but it seems unusual to me. 

[alemabrahao]

The device connected to the port won't always consume its full power; it will depend on the features being used. However, you are indeed experiencing strange behavior.

In this case, I suggest you update to the latest stable version, and if the problem persists, it's best to open a support case.

[Mloraditch]

As @alemabrahao states devices will only consume as much as necessary for current operation but may state they request more.

However as far as overall allocation MS code handles that differently than the underlying IOS-XE on CS firmware. MS switches will happily provide power as long as the actual consumption is below the total available and allow the total requested to be over the max available. IOS-XE, however, budgets on the requested power which is different. An AP may request 60W but in most operations only use 20ish. MS looks at the 20W, IOS-XE looks at the 60. A 720W MS switch would allow 36 of those devices, an IOS-XE, 12.

The blue box on this page calls this out:

https://documentation.meraki.com/Switching/MS_-_Switches/Operate_and_Maintain/How-Tos/PoE_Support_on...

While there are some ways to deal with this in native mode (manual poe budgeting), Im not sure you can do that in Meraki managed mode. Support may be able to do something on the backend.

[Willrockhopper]

This is good to know, thanks for the info. 

[PhilipDAth]

The "CS" code train is "almost" legacy now.  It gets zero love.

Is there any chance you could upgrade to IOS XE 17.15.4.1?  That is where all the work and bug fixes are going.

[Willrockhopper]

We would love to upgrade but are holding off until it becomes a stable release. At Cisco Live we heard December from one person, and March from another.

[IvanJukic]

@Willrockhopper ,

Just wanted to add that CS17.2.2 does have a PoE fix. Might be related.