Cisco SG350X-24P shows port flapping

[nib2025]

Hi

We have a setup where 14 cameras with gigE interface and poe are connected to a cisco SG350X-24P switch.

The switch is setup with jumboframes and flowcontrol.

The problem is that some of the ports are flapping once in a while.

Output from the log is showed in the attached image.

Sometimes the camera reconnects again after a while. Other times the camera just stays disconnected, or speed set to 100.

We have exchanged cables, and connectors, but the problems just seems to move to another camera/port.

The problem occurs too, even though we don't do any recordings, and therefor are not overloading the the network.

Anyone know what could be the problem?

[marce1000]

               - How are the ports configured ?

  M.

[nib2025]

Hi Marce
Thank you very much for your quick response.
Our ports are configured with:

flowcontrol on

spanning-tree portfast

N.

[marce1000]

  - Disable Auto Smartport on the interfaces and or globally on the switch; check if that can help ,

 M.

[nib2025]

Hi Marce

Thank you very much, we will try that out
N.

[Jens Albrecht]

Hi @nib2025,

the SG350X-24P switch has a PoE power budget of 195 Watt but with 14 cameras connected you are obviously exceeding this.

For each PoE device the switch provides 15.4 Watt per port so with 14 cameras the switch needs to provide 215.6 Watt of PoE power which is beyond the capabilities of this device.

As a result your problem randomly jumps from port to port because the switch simply cannot provide PoE to all 14 ports at the same time.

So you either need to move 2 cameras to another switch or replace the switch e.g. with the SG350X-24MP model which has 382 Watt PoE power budget. Hence this model can provide PoE to all 24 port simultaneously.

HTH!

[nib2025]

Hi Jens

Thank you very much for your response.

The cameras we are using are rated for 4.8 Watt each. That should for 14 cameras be below 185 Watt which I find in the datasheet. Unless the switch still wants to save 15.4 Watt for each port?

N.

[Jens Albrecht]

Hi @nib2025,

by default switches provide 15.4 Watt per port if a PoE device is detected and hence deduce this from their power budget.

There are 2 ways to change this default behavior:

• Use LLDP to negotiate the power consumption. This protocol allows a PoE device to tell the switch how much power it actually consumes so that the switch only deduces this amount from its budget allowing you to connect more devices.
• Statically configure the ports to only provide e.g. 6 Watt per port which also allows you to add more PoE devices.

You can check the current power consumption on your switch with the "show power inline" command to see how much power budget is still left. If it is down to "0" then the switch cannot provide power to any additional port.

Use the command "power inline max 10000" on each port to limit the power per port down to only 10 Watt, for example. No need to be too aggressive to make sure that even in case of long cables or somewhat dirty connectors the device still gets enough power.

LLDP can be enabled globally using the command "lldp run" to negotiate the power consumption if the cameras also support this protocol.

As a first step I would enable LLDP and check with the command "show power inline" whether the switch adjusts the power down to 4.8 Watt or not. If not, then you need to configure the ports manually to reduce power.

HTH!

[nib2025]

Hi @Jens Albrecht 
Thank you very much for your response
The output from "show power inline" is attached
It seems that all (used) ports are having the correct power consumption.
I am not sure my cameras support LLDP (I can't find information about it in the user manual).
I have attached the output from LLDP neighbors and configuration as well.
Running LLDP neighbors does not list my cameras.

N.

[Jens Albrecht]

Hi @nib2025,

the switch seems to detect the cameras as power class 2 even though they to not appear as LLDP neighbors.

Are all 14 cameras the same model? It seems a bit strange that the power consumption varies between 3.5 and 4.2 Watt. You initially mentioned that sometimes the port speed goes down to 100MB which might indicate problems with auto-negotiation.

So to exclude PoE as a reason I suggest adding the following 2 lines to your port configurations:

switchport mode access
power inline static 7000

This ensures that the switch always provides up to 7 Watt on each port without any negotiation.

HTH!