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Aastra 6753i phones fail PoE negotiaion on Cisco switch ports

Gasmanz
Posts: 235
 Member Since:
2007-09-04
Submitted by Gasmanz on Tue, 01/26/2010 - 3:19am.

We have a customer that has a Cisco WS-C3760-48PS 48 port PoE switch powering their Aastra 6731i and 57i phones which are negotiating their power requirements as 4w. They have just tried to install some new 6753i phones and they are negotiating their power requirements as 15.4w. This is causing their switch to run out of power for PoE as it is reserving the 15.4w for all the new phones. The phones have been tried with 2 firmware versions 2.5.0 and 2.5.3 but it still the fail back to 15.4w. The Cisco switch also has a late 2009 IOS. They have tried it on 3 different Cisco PoE switches.

Is there a known issue that causes the 6753i phones to fail the power requirement negotiations on Cisco PoE switch ports?

This is really urgent if someone is able to help.

Thanks

‹ BLF with "Device and User" 57i Sprecode Parking ›
--

Graham Campbell

FtOCC Tech Certified
Hi-Tech Solutions Ltd.
Auckland
New Zealand



aastra4
Posts: 59
 Member Since:
2007-02-27
Power Consumption
Fri, 01/29/2010 - 5:04am

Hi,

All the 675xi phones are PoE Class 0. This means that the switch will budget 15.4W for each device. The actual power consumption is lower than 15.4W and depends on various factors (backlight, state of LEDs, speakerphone, ringer, expansion modules connected to phone, ...).

Refer to this thread to see the max power consumption:
http://trixbox.org/forums/vendor-forums-certified/aastra-endpoint...

The 6731i phone is a PoE Class 1 device.

Regards,

Luca



Gasmanz
Posts: 235
 Member Since:
2007-09-04
Why?
Mon, 02/01/2010 - 6:22pm

Why would you want a switch to budget 15.4W for a device that only uses

There are no PoE switches that can supply 15.4W to every port, so are you saying that with the 675xi phones we won't be able use every port on the PoE switch for phones? Why has this been changed for the new 675xi phones? The previous phone models worked well when negotiating their power requirements and allowed us to use all the ports on the PoE switches for phones?

Regards,

--

Graham Campbell

FtOCC Tech Certified
Hi-Tech Solutions Ltd.
Auckland
New Zealand



aastra4
Posts: 59
 Member Since:
2007-02-27
Exp. Modules
Wed, 02/03/2010 - 1:40am

Hi,

The 675xi phones support - depending on the model - up to 3 LCD expansion modules (M675i). Depending on the state of the phone and the back light of the LCDs, the power consumption can be higher than 5W and therefore the phone's can't be Class 1. Since the switch doesn't know how many modules are connected, it needs to budget enough power.

The 675xi phones have always been Class 0, there hasn't been any change.

Regards,

aastra4



Gasmanz
Posts: 235
 Member Since:
2007-09-04
Expansion Modules
Sun, 02/07/2010 - 4:52pm

When you add an expansion module to the phones you need to reboot them anyway so it could then advise the switch port of its new power requirements, instead of the phone just saying "one day I might need 15.4w so you better keep it all in reserve for me".

If this is the method Aastra have chosen to use with their new phones we will no longer sell them to our customers as no switch manufacturers support 15.4w on all ports.

Regards,

--

Graham Campbell

FtOCC Tech Certified
Hi-Tech Solutions Ltd.
Auckland
New Zealand



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