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Author Topic: 5520-48t-PWR POE Issue  (Read 3906 times)

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Offline mikeb

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5520-48t-PWR POE Issue
« on: July 17, 2014, 10:13:20 PM »
Hello,

I just got a 5520-48t and I have a cisco air 1252 AP attached to it which requires POE. I am getting an error from the AP that not enough power is getting to it. On the switch side I cannot seem to change the port max wattage above 16 every time I try it says wrong value.

Any guidance would be EXTREMELY appreciated.

Thanks

Mike


Offline Johan Witters

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    • BKM Networks
Re: 5520-48t-PWR POE Issue
« Reply #1 on: July 18, 2014, 08:11:44 AM »
Hello Mike,

The 5520-48T-PWR is an older model switch and only supports the 802.3af power standard. This is limited to approx 15.4W of power per port.

If the access points requires more you need a different type of switch. Your 1252 AP requires a switch capable of delivering at least 20W of power according to the specs. You might get it working on the 5520 if the unit has only 1 radio. Otherwise you will need a different switch, direct power supply on the ap, or a 802.3at rated power injector.

Greetz,

Johan
Kind regards,

Johan Witters

Network Engineer
BKM NV

Offline mikeb

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Re: 5520-48t-PWR POE Issue
« Reply #2 on: July 18, 2014, 08:26:44 AM »
Thanks very much. Do you have any recommendations for a switch that is a bit older (i.e. less expensive) but can support the APs?

Much appreciated.

Mike

Offline Johan Witters

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    • BKM Networks
Re: 5520-48t-PWR POE Issue
« Reply #3 on: July 18, 2014, 08:34:33 AM »
Not really,

most 803.3at (PWR+) switches are current models with Avaya, but if it is for only a few ports you could use the ERS3510GT-PWR+. It's a 8 port gigabit with PWR+ switch, ports 9+10 are sfp slots. It's available at around 650$..

A 2nd option would be to buy a power injector for the ap: in that case you can disable PoE on the switch port, link a cable from the switch to the injector, and from the injector to the ap... The model needed for your ap is Cisco AIR-PWRINJ4. If you only have 1 ap, that would the cheapest solutions as the injector cost approx. 100$

Greetz,

Johan
Kind regards,

Johan Witters

Network Engineer
BKM NV

Offline mikeb

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Re: 5520-48t-PWR POE Issue
« Reply #4 on: July 18, 2014, 01:30:12 PM »
Thanks - much appreciated.

Mike

Offline TankII

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Re: 5520-48t-PWR POE Issue
« Reply #5 on: July 25, 2014, 09:03:13 AM »
I'd get an injector - it's the least-cost option, especially if you have only one AP.

TankII

Offline mikeb

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Re: 5520-48t-PWR POE Issue
« Reply #6 on: August 07, 2014, 11:31:57 AM »
Thanks for the info. I got a 802.3at POE injector but because it wasn't Cisco proprietary it didn't work - still showed reduced power even though the injector could put out full 802.3at. Apparently Cisco uses something a little different than the standard and a proprietary way of knowing when to indicate "full power". I ended up getting the pwrinj4 and that worked fine.