New 7961G-GE phones don't work with 3550 10\100 PoE switches?

Answered Question
Sep 5th, 2007

Approximately 1/3 of the access switches at our central office are model WS-C3550-24PWR-SMI switches. We have recently started purchasing the new 7961G-GE phones and it appears through testing that the new phones do not work with the 3550 switches. Watching the logs on the 3550 show that PoE is granted to the device, and the phone does appear to start booting up (speaker button lights, then all buttons light, then the speaker button), and the phone continues to cycle this way but there is never any display on the LCD. The switch logs indicate that PoE was granted but the line protocol never came up. If I connect the 7961 to a 10\100 3560PoE the phone boots normally. I have tested the phones on many different 3550 switches, all with the same result. We are running IOS v12.2(25)SEE2 on all the 3550s. Could this be a bug or is this by design?

I have this problem too.
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Correct Answer by rob.huffman about 9 years 3 months ago

Hi Jason,

Unfortunately the 3550 - 24 PWR only supports Cisco prestandard PoE and the 7961G-GE requires IEEE 802.3af PoE . Here are a few reference docs with this note;

Cisco PoE Product Snapshot

http://www.cisco.com/en/US/netsol/ns340/ns394/ns147/ns412/netbr09186a00801f4329.html

Catalyst 3550-24PWR

24 10/100 Cisco prestandard PoE ports and 2 GBIC-based Gigabit Ethernet slots

http://www.cisco.com/en/US/docs/switches/lan/catalyst2950/software/release/12.1_19_ea1c/release/notes/OL543002.html

Cisco Catalyst 3550 24 PWR (Cisco prestandard PoE only)

http://www.cisco.com/en/US/products/ps6021/prod_brochure0900aecd8017bf5f.html

Q. What IP phone models support the IEEE standard method of powered device detection?

A. These Cisco IP phones support IEEE 802.3af PoE:

7961G-GE

7971G-GE

7941G

7931G

7911G

7941G-GE

From this new doc;

Power over Ethernet (PoE) Power Requirements FAQ

http://www.cisco.com/en/US/products/hw/phones/ps379/products_qanda_item09186a00808996f3.shtml

Hope this helps! (I know its a bummer :(

Rob

Edit: Mahesh, you must slow down for me to keep up :) My typing skills are zero!

Correct Answer by mchandak about 9 years 3 months ago

The reason 7961G-GE phone does not work with 3550 is because 3550 only supports Cisco Pre-Standard Power supply whereas 7961G-GE phone only support IEEE 802.3af power supply. Please check the Data Sheet (Power Requirement Section for 7961G-GE Phones)

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

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akascarface Mon, 10/22/2007 - 13:21

Guys you can get it to work. I have a 7971G working off of a 3550PoE switch you have to put in the cmd: power inline delay shutdown 20 initial 300

beacomronald Sun, 05/02/2010 - 08:35

YOU are the man. I bought 4 Cisco 7971G-GE phones and I thought I got screwed but that command works like a charm!!!!

Thanks!!!!

Correct Answer
rob.huffman Wed, 09/05/2007 - 12:44

Hi Jason,

Unfortunately the 3550 - 24 PWR only supports Cisco prestandard PoE and the 7961G-GE requires IEEE 802.3af PoE . Here are a few reference docs with this note;

Cisco PoE Product Snapshot

http://www.cisco.com/en/US/netsol/ns340/ns394/ns147/ns412/netbr09186a00801f4329.html

Catalyst 3550-24PWR

24 10/100 Cisco prestandard PoE ports and 2 GBIC-based Gigabit Ethernet slots

http://www.cisco.com/en/US/docs/switches/lan/catalyst2950/software/release/12.1_19_ea1c/release/notes/OL543002.html

Cisco Catalyst 3550 24 PWR (Cisco prestandard PoE only)

http://www.cisco.com/en/US/products/ps6021/prod_brochure0900aecd8017bf5f.html

Q. What IP phone models support the IEEE standard method of powered device detection?

A. These Cisco IP phones support IEEE 802.3af PoE:

7961G-GE

7971G-GE

7941G

7931G

7911G

7941G-GE

From this new doc;

Power over Ethernet (PoE) Power Requirements FAQ

http://www.cisco.com/en/US/products/hw/phones/ps379/products_qanda_item09186a00808996f3.shtml

Hope this helps! (I know its a bummer :(

Rob

Edit: Mahesh, you must slow down for me to keep up :) My typing skills are zero!

JASON WELCH Wed, 09/05/2007 - 12:49

Thank you both ver much for your replies. One last question on this though: from the Q&A listed in your response the 7941G only supports 802.3af, but we do have several of these phones as well (one at my desk) and they work fine on the 3550s?

rob.huffman Wed, 09/05/2007 - 12:53

Hi Jason,

That is surely a misprint, I have 7941G's on 3550's as well but 7961G-GE's will not power up. I will try to find some better references :)

Take care,

Rob

Paolo Bevilacqua Wed, 09/05/2007 - 13:45

I can say with some confidence that the difference is due to the fact the phones not working with pre-standard are gigabit ethernet phones. We know that GE uses all 4 pairs vs. only 2 for a 100 mbps phone. And the other pairs were used for pre-standard PoE.

akascarface Mon, 10/22/2007 - 13:22

Guys you can get it to work. I have a 7971G working off of a 3550PoE switch you have to put in this cmd on the port: power inline delay shutdown 20 initial 300

stroutjustin Fri, 04/11/2008 - 10:42

I concur akascarface. This command on the port will power up the 7961, 7971, and even the 7975g phones. Thanks for posting this. It saved me.

kmusgraves Thu, 09/25/2008 - 09:38

Hello Rob,

I have this same switch (3550)but I am not using POE for my 7971G/7965G phones. I still can't my phones to register with Call Mangager(6.1.1). The phone pull an IP address but will not register. What could be my problem?

Doc Musgraves

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