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7971g-ge and 7941g dont power up with a Catalyst 3524-PWR XL

Hey all,

I make some test to prepare a move to VOIP in my company and im kind of beginner with this technology.

i have a Switch Catalyst 3524-PWR XL.

and 3 type of ip-phones:

cp7940g

cp7941g

cp7970g-ge

I made my test with 7940g everything was working fine, then i received 2 new models cp7941g and cp7970g-ge. But when i plug the ethernet cable(connected to switch 3524) the phone dont power on.

i checked on some site and try to active power inline auto on some ports.. but it's change anything.

i dont have any power DC48V... :-P

Can anyone please help.

thanks a lot

1 ACCEPTED SOLUTION

Accepted Solutions
Hall of Fame Super Gold

Re: 7971g-ge and 7941g dont power up with a Catalyst 3524-PWR XL

Hi,

the CE500 is the cheaper switch with PoE made by cisco. Is not easy to find an alternative, e.g. switches by linksys have PoE for a limited number of ports only, and do not support pre-standard, etc...

hope this helps, please rete post if it does!

5 REPLIES
Hall of Fame Super Red

Re: 7971g-ge and 7941g dont power up with a Catalyst 3524-PWR XL

Hi Xavier,

I have always found this hard to explain, but I will try :)

Cisco PoE switches are not all created equal. Older models like the 3524-PWR XL that you are using only support what is called "Cisco Pre-Standard PoE" and do not support the IEEE Standard which is referred to as IEEE 802.3af PoE.

Now for the fun part?? Different models of Cisco IP Phones have different PoE requirements sometimes called "Classes" These Classes require different amounts of power supplied by either "Cisco Pre-Standard PoE" or IEEE 802.3af PoE. New Models of Cisco switches are backwards compliant to support both PoE modes but Old Models like the 3524 only support the one Pre-Standard mode (confused yet?)

So when using the Old models like the 3524 you always have to be careful of what IP Phone type you can or can't support.

Have a look;

The 7940G/7941G and 7960G/7961G are class 2 devices (7.7 watts) power requirement.The 7941G works with Cisco Pre-standard PoE and with IEEE 802.3af PoE.

From this doc;

http://www.cisco.com/en/US/customer/products/hw/phones/ps379/products_data_sheet0900aecd802ff012.html

The 7941G-GE/7961G-GE/7970G-GE phones are class 3 devices (15.4 watts) and only support IEEE 802.3af PoE.These are not configurable settings.

From this doc;

http://www.cisco.com/en/US/customer/products/hw/phones/ps379/products_data_sheet0900aecd802fefd4.html

Hope this helps!

Rob

Community Member

Re: 7971g-ge and 7941g dont power up with a Catalyst 3524-PWR XL

Thank you for your help rob! :-)

I see now... why i still don't see the beautiful color of the 7971 :-P

Anyway i planned to buy another switch, so i guess its the good moment, i saw the WS-CE500-24PC... but do you have another recommendation ?

i try to find the cheaper one with 24ports Poe ieee 802.3af, no other options/functionalities needed.

thanks

Hall of Fame Super Gold

Re: 7971g-ge and 7941g dont power up with a Catalyst 3524-PWR XL

Hi,

the CE500 is the cheaper switch with PoE made by cisco. Is not easy to find an alternative, e.g. switches by linksys have PoE for a limited number of ports only, and do not support pre-standard, etc...

hope this helps, please rete post if it does!

Community Member

Re: 7971g-ge and 7941g dont power up with a Catalyst 3524-PWR XL

-

Hall of Fame Super Red

Re: 7971g-ge and 7941g dont power up with a Catalyst 3524-PWR XL

Hi Xavier,

You are very welcome :) I'm surprised that rambling made any sense! Just thought that I might add that in a pinch the 7971 can also be Powered locally with a power adapter (CP-PWR-CUBE-3=) which is pretty darn cheap.

As shown in this doc;

http://www.cisco.com/en/US/docs/voice_ip_comm/cuipph/7970g_7971g-ge/6_0/english/install/guide/70instlX.pdf

Hope this helps!

Rob

Nice to see you back Paolo (another vacation?? :) Huff

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