PoE - Physically Separating PoE Devices

[siriusmeraki]

We had a firmware upgrade a while back and afterwards PoE draw was too much which shut down certain ports. Had to reboot switch.

Would spreading out the PoE devices across the switch decrease load in any way?

Right now x6 cameras are clustered in ports 38-42. Would placing them in 1, 6, 12, 18, 24, 30 create less issues? As far as I know, there's a single electrical line to the panel so this wouldn't change anything.

Is it "bad" to cluster PoE devices in ports right next to each other?

[Ryan_Miles · Accepted solution]

The PoE budget applies to the switch as a whole. The port numbering does come into play when you run over the power limit however and lower port numbers are given priority. Meaning higher number ports will have PoE denied.

https://documentation.meraki.com/MS/Other_Topics/PoE_Support_on_MS_Switches#PoE_Power_Budgeting

[siriusmeraki]

Good to know, it's the little details that are important!

[PhilipDAth]

I don't understand how you are having this issue.

If you had 15.4W cameras you would be drawing up to 90W of power.  You have a 48 port switch, and the smallest PoE budget available is 370W.  So your load should be considerably less than your capacity.

Even if your cameras used double the power, you still would not have an issue.

So I wonder if you actually have a cable or camera issue.  I would try using the cable testing in your Meraki switch and see if it can detect any impedance issues on the cabling.

https://documentation.meraki.com/MS/Monitoring_and_Reporting/Using_the_Cable_Test_Live_tool

I would try monitoring the PoE load on the switch.  Unplug all the cameras.  And then plug them in one by one.  See if the load suddenly jumps when you plug in a particular camera.  Wait a minute or two after plugging in each camera to give it time to complete booting.

[siriusmeraki]

I will do some more testing, thank you so much for your advice!

[JoDawg007]

Putting all your PoE devices in adjacent ports is certainly not a problem. We do that a lot with our customers to aid in tracking where APs, Cameras, and phones are at based on port ranges. It is recommended to load balance PoE devices over multiple switches just to have some resiliency if a switch were to go down, but there's no need to physically separate PoE devices over ports on the same switch.

What does your Power tab say on the switch for PoE Budget? Is it indicating you're over budget? How many PoE devices do you have on that switch total? I also second the statement by PhilipDAth about tracking a specific camera that may be using more PoE than the rest. You can see that information on the port-level pages when looking at the switch in the Dashboard. Toward the bottom of the page, there will be a PoE Usage line indicating how much that port is using.

[siriusmeraki]

Some of the cameras have different specs I believe so I will do some further investigating. Thanks so much for your time!

[ls08]

I think I’m experiencing this issue and I can reproduce it with only a MG41. I read a post on the MG section and tried to connect a MG41 to a MS120-48LP. My MG41 would get power, and on the port status the lightning symbol appears. Eventually the lightning disappeared and the MG41 was off. I flipped the connection with a Cisco 8811 IP phone. The phone powers on and I see the boot logo. The MG41 is now on the port the phone and powers on, but then turns off after a few seconds. The port turns off and also the 8811. I also have a MR access point on the switch and that loses power. Now no other port works with POE and the power tab on the switch on then dashboard does not show the POE  consumption. Just a blank screen. 

Rebooting the switch fixes it and I try to reproduce the issue again. I plug in MG41 to port 48, 8811 on port 45 and MR back on port 37. I do the phone and MR first and they boot and connect. I now do the MG41 and the device powers on. On the port status I see it drawing 1.3 w to .9w or 0. This cycles for a few seconds then eventually 0 and the device stays off. I flip the 8811 and  MG41. Phone is powering on and MG. Eventually everything POE turns off phone MR and MG. Reboot fixes the issue. 

This MG41 works on a MX85 it did prior to connecting to the switch. I’ve read other posts of users connecting to the switch on their network to get the MG41 POE power. So this is supposed to work, but it looks like the switch is having issues. 

MS 14.33.1

[siriusmeraki]

Thanks for the input.