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How to use PoE with Cisco injectors?

21 Apr 2010

markm

United Kingdom

We use a splitter (from Silver Telecom) which is compliant to IEEE 802.3af which seems to work well with most injectors and switches.  Recently we have had problems with Cisco injectors which won't supply power to our device.  I believe Cisco have their own Power over Ethernet scheme which is different to 802.3af.  I have been asked if it's possible to get a splitter to work with both Cisco injectors and 802.3af injectors. 

Does anyone here have any ideas?

Replies

markm

United Kingdom
2 years ago

Thanks. That link gives a lot of useful information.  We tried many of the suggested 'tricks' but failed to make the injector give power.  My reasoning is that the injector has a discovery protocol which doesn't see our device so doesn't enable power.

We swapped out the Cisco injectors for 802.3af ones and all is fine. Only problem now is customer has bought another 100 units and they are using Cisco switches!  Fingers crossed they are 802.3af compliant ...

Mark Cundle

United Kingdom
2 years ago

A great thread here may help...possibly?

http://www.voip-info.org/wiki/view/Cisco+POE

It certainly helped with my understanding of PoE at least!

LStacey

United Kingdom
2 years ago

According to the application notes, Cisco support 802.3af and 802.3at.

More details here:

http://www.cisco.com/en/US/docs/wireless/technology/poe/technical/refere...

markm

United Kingdom
2 years ago

I think we must have been unlucky because the injector was AIR-PWRINJ3 which as far as I can see isn't 802.3af.