Connecting POE Switch To A POE Port On An NVR?

Undisclosed #1

08/06/15 08:12am

Hi,

I'd like your advice please. I have a 16ch NVR with 8 POE ports built in. I want to connect a separate 8 POE switch to the NVR's builtin POE ports. Will this be OK? And if yes, will it be ok/stable in the long run with no power issues, burn outs, etc?

Thanks

Undisclosed Integrator #2

08/06/15 09:34am

You can turn off power to PoE ports in some switches. Else I think you may run into problems as the two units are trying to negotiate who is to send power and who is to receive. If the switch has an "uplink"port, those are usally non-PoE , then you can use that port.

Come to think of it, I have successfully plugged a Xyzel PoE switch to a Cisco PoE port with not a problem.. Truth is I wasn't even thinking of the implications :)

Chris Dearing

IPVMU Certified | 08/06/15 09:34am

Hello 1.

As long as both the switch and NVR are listed as 802.3.af compliant, there will be no power exchange between the two.

There are a few switches out there, (Ubiquiti, MicroTik), that provide "always on" passive 24 or 48v POE that you would want to avoid.

Even then I'm not sure that anything would actually happen to the NVR, as the NVR ports are most likely only using pins 1,2,3,6 for both power and data and the switches passive POE would be coming in on pins 4,5,7,8.

I'm sure I don't want to find out though.

Undisclosed #3

In reply to Chris Dearing | 08/06/15 10:20am

Agreed, if both the units are "real" PoE devices then there will zero issues with this.

If either unit is a passive power injector and not actual PoE then you can still connect them, but I'd recommend using/making a patch cable that only has pins 1,2,3,6 wired (I've never seen one of the passive injectors actually do power on the data pairs).

Undisclosed Integrator #2

In reply to Chris Dearing | 08/06/15 12:08pm

That explain why there is no issue with the 2 PoE switches being conected via PoE ports ...

Very informative..

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