PoE Using A 7937G With A 3560?

djfunz

Hello everyone. We have a Cisco Unified IP Conference Station 7937G that I'm trying to power using PoE. Can anyone confirm if the Cisco 3560 will power up this phone? I've tried and it doesn't appear to work.

I found a similar thread and a member mentions that "If its not class 3 (or older POE switch) then it wont power up." I know the 3560 is pretty old so I'm curious.

Thanks.

pitviper

The 3560s do indeed support IEEE 802.3af. I would check to make sure that the switch has enough power remaining for the device (show power inline)

djfunz

Thanks for the information pitviper. It does indeed have enough power but the phone will not boot. I tried multiple ports with no luck.


Switch#sh power inline
Available:370.0(w) Used:0.0(w) Remaining:370.0(w)


Interface Admin Oper Power Device Class Max
(Watts)

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Fa0/1 auto off 0.0 n/a n/a 15.4
Fa0/2 auto off 0.0 n/a n/a 15.4
Fa0/3 auto off 0.0 n/a n/a 15.4
Fa0/4 auto off 0.0 n/a n/a 15.4
Fa0/5 auto off 0.0 n/a n/a 15.4
Fa0/6 auto off 0.0 n/a n/a 15.4
Fa0/7 auto off 0.0 n/a n/a 15.4
Fa0/8 auto off 0.0 n/a n/a 15.4
Fa0/9 auto off 0.0 n/a n/a 15.4
Fa0/10 auto off 0.0 n/a n/a 15.4
Fa0/11 auto off 0.0 n/a n/a 15.4
Fa0/12 auto off 0.0 n/a n/a 15.4
Fa0/13 auto off 0.0 n/a n/a 15.4
Fa0/14 auto off 0.0 n/a n/a 15.4
Fa0/15 auto off 0.0 n/a n/a 15.4
Fa0/16 auto off 0.0 n/a n/a 15.4
Fa0/17 auto off 0.0 n/a n/a 15.4
Fa0/18 auto off 0.0 n/a n/a 15.4
Fa0/19 auto off 0.0 n/a n/a 15.4
Interface Admin Oper Power Device Class Max
(Watts)

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Fa0/20 auto off 0.0 n/a n/a 15.4
Fa0/21 auto off 0.0 n/a n/a 15.4
Fa0/22 auto off 0.0 n/a n/a 15.4
Fa0/23 auto off 0.0 n/a n/a 15.4
Fa0/24 auto off 0.0 n/a n/a 15.4
Fa0/25 auto off 0.0 n/a n/a 15.4
Fa0/26 auto off 0.0 n/a n/a 15.4
Fa0/27 auto off 0.0 n/a n/a 15.4
Fa0/28 auto off 0.0 n/a n/a 15.4
Fa0/29 auto off 0.0 n/a n/a 15.4
Fa0/30 auto off 0.0 n/a n/a 15.4
Fa0/31 auto off 0.0 n/a n/a 15.4
Fa0/32 auto off 0.0 n/a n/a 15.4
Fa0/33 auto off 0.0 n/a n/a 15.4
Fa0/34 auto off 0.0 n/a n/a 15.4
Fa0/35 auto off 0.0 n/a n/a 15.4
Fa0/36 auto off 0.0 n/a n/a 15.4
Fa0/37 auto off 0.0 n/a n/a 15.4
Fa0/38 auto off 0.0 n/a n/a 15.4
Fa0/39 auto off 0.0 n/a n/a 15.4
Fa0/40 auto off 0.0 n/a n/a 15.4
Fa0/41 auto off 0.0 n/a n/a 15.4
Interface Admin Oper Power Device Class Max
(Watts)

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Fa0/42 auto off 0.0 n/a n/a 15.4
Fa0/43 auto off 0.0 n/a n/a 15.4
Fa0/44 auto off 0.0 n/a n/a 15.4
Fa0/45 auto off 0.0 n/a n/a 15.4
Fa0/46 auto off 0.0 n/a n/a 15.4
Fa0/47 auto off 0.0 n/a n/a 15.4
Fa0/48 auto off 0.0 n/a n/a 15.4

djfunz

I also tried another IEEE 802.3af switch. The C3560-IPBASEK9-M.

It seems to at least recognize that an IP device was connected to the different ports I tried but displayed the following error.

%ILPOWER-3-CONTROLLER_PORT_ERR: Controller port error, Interface Fa0/1: Power Controller reports power Tstart error detected

I wish I had the CP-PWR-CUBE-3 with the Cisco Unified IP Conference Station 7937G Power Splitter to at least see the phone boot.

shodown

I just did this today. They work, something is wrong with the config or the phone. How many phones do you have plugged in? How long is the cable? Have you took the phone directly to the switch? Is this a 7937 off ebay?

djfunz

Hi shodown, this is purely for testing purposes. I used the Ethernet cable included with the phone.

Cisco 7935/7936 Shielded PoE Cable, CP-7936-PWR-CBL

-I'll guess it's at least 15'.
-It's just one phone connected to a 3560 with nothing else connected to the SW.
-The phone is connected directly to the SW.
-I have tried multiple 7937Gs
-The phones are from a qualified vendor.

Please elaborate what you mean by something being wrong with the config. CDP is enabled on the ports by default right? Plug and boot is all I understood needed to be done for functionality.

djfunz

I feel a bit embarrassed right now. I just had two bad phones it turns out. I tested a third phone and it booted up no problem. Thanks for taking the time to reply guys.

shodown

it happens to the best of us. With 2 bad phones you did the right thing. Its very, very rare for that to happen. It has never happend to me in IT. Back when I was doing electronics I had 3 bad Diodes in a row, We kept thinking it was something else for weeks and weeks, but it turned out that lot had a high failiure rate.

theodoxa

The 3560 series support IEEE Standard PoE. I don't know if they support the older Cisco Prestandard or not (I haven't tried running any phones off my 3560 yet). But, the 3550 series only supports the older Cisco Prestandard. I ran into that problem when I bought a Cisco AP and then discovered that it would only run on the newer IEEE Standard PoE. At the time, I only had 3550s. Strangely, I'm pretty sure the AP itself was archaic.

pitviper

Wow, what luck! I've only had 1 bad phone of the thousands the I've deployed, and honestly I think it was inadvertently unplugged during a firmware update.