7961G and Power Consumption

[palves]

I have a 3750 with 48 ports.

I can only use 24 ports with 7961's. After that, no more power can be drawn from the switch.

I noticed that the 7961's are using 15.4watts of power.

7960's used 7.7watts mode.

Can the 7961's use 7.7watts mode?

This is not configurable on the switch.

Is it configurable on the IP Phone??

I can't find any documentation on Cisco's web site in regards to 7961 power consumption (only 7960 power consumption).

thanks,

Paul

[baytan]

Nothing can be done about power mode of 7961's at that point. They are "PoE Class 3 Devices" and Catalyst 3750-48PS can support 48 PoE Class 2 Devices "like 7960" or 24 PoE Class 3 Devices "like 7961".

[Rob Huffman]

Hi Paul,

Are these phones 7961G or 7961G-GE? The 7961G are a class 2 device (7.7 watts) and the 7961G-GE phones are a class 3 device (15.4 watts).These are not configurable settings.

Each Cisco Catalyst 3750-24PS or Cisco Catalyst 3750-48PS switch can optionally detect the PD Power Classification signature and budget the appropriate power. This reduces the maximum power that must be budgeted by the switch and provisioned in the wiring closet. The Cisco Catalyst 3750 PoE switches have **370W**(this is enough for 48 class 2 devices @ 7.7 watts 48x7.7 = 369.6 watts) available for Power over Ethernet, which is shared by all 24/48 ports. The switch allocates the maximum power a PD needs.

Have a look at these Cisco docs;

Cisco Unified IP Phone 7961G

Power Requirements The phone is interoperable with Cisco Pre-standard PoE and with IEEE 802.3af PoE (the phone is a Class 2 device); 48 VDC is required; it can be supplied locally at the desktop using an optional AC-to-DC power supply (part number CP-PWR-CUBE-3=).

From this doc;

http://www.cisco.com/en/US/products/hw/phones/ps379/products_data_sheet0900aecd802ff020.html

Cisco Unified IP Phone 7961G-GE

Power Requirements The phone supports the IEEE 802.3af PoE (the phone is a Class 3 device) standard; 48 VDC is required; it can be supplied locally at the desktop using an AC-to-DC power supply (part number CP-PWR-CUBE-3=).

The Cisco Unified IP Phone 7961G-GE supports IEEE 803.af Power over Ethernet (PoE). It also can be powered locally with a power supply (part number CP-PWR-CUBE-3). **Note: The Cisco Unified IP Phone 7961G-GE does not support Cisco Pre-standard PoE.**

From this doc;

http://www.cisco.com/en/US/products/hw/phones/ps379/products_data_sheet0900aecd802ff030.html

Hope this helps!

Rob

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[scott.brown]

Did you ever get an answer to this?

I'm looking for the same info

[Rob Huffman]

Hi Scott,

When we were deciding on what model of 7900 series phones we were going to purchase for our next rollout this question came into play because of the number or older switches we have that only supply Cisco Pre-standard PoE.

We did go with 7941G's and 7961G's because of the fact that they are Class 2 devices ie:

7.7watts vs Class 3 devices 15.4watts (7941G-GE AND 7961G-GE)

Specifications of Cisco Unified IP Phone 7961G

The phone is interoperable with Cisco Pre-standard PoE and with IEEE 802.3af PoE (the phone is a Class 2 device); 48 VDC is required; it can be supplied locally at the desktop using an optional AC-to-DC power supply (part number CP-PWR-CUBE-3=).

From this Data sheet;

http://www.cisco.com/en/US/products/hw/phones/ps379/products_data_sheet0900aecd802ff020.html

Specifications of Cisco Unified IP Phone 7961G-GE

The phone supports the IEEE 802.3af PoE (the phone is a Class 3 device) standard; 48 VDC is required; it can be supplied locally at the desktop using an AC-to-DC power supply (part number CP-PWR-CUBE-3=).

From this Data sheet;

http://www.cisco.com/en/US/products/hw/phones/ps379/products_data_sheet0900aecd802ff030.html

Hope this helps!

Rob

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