New 7937G keeps power cycling

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Apr 19th, 2010
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I have a 7937 hooked up to a CAT3550 and we have PoE runing to that device but it keeps on power cycling. I tried to extend the power on the 3550 by issuing the following command SWITCH#power inline delay shutdown 20 initial 300. All this does is it powers up the 7937 for aprox. 20sec then it goes back to shutdown and tries to power up again.


Any ideas?


Julien    

Correct Answer by Rob Huffman about 7 years 3 days ago

Hi Julien,


The reason the 7937 phone does not work with the 3550 is because the 3550 only supports Cisco Pre-Standard Power whereas the 7937 phone only supports IEEE 802.3af power


PoE power snapshot


http://www.cisco.com/warp/public/cc/pd/si/casi/ca6000/prodlit/psnap_br.pdf


7937 Data Sheet


http://www.cisco.com/en/US/prod/collateral/voicesw/ps6788/phones/ps379/ps8759/product_data_sheet0900aecd806e021a.html



Cheers!

Rob



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CHRIS CHARLEBOIS Mon, 04/19/2010 - 09:43
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Does it manage to pull an IP address from DHCP?  Does it contact the TFTP server?  I'm seen issues with IP phones that continually reboot because the phone cannot find the right version of firmware to upgrade to.  Although 20 seconds is awfully short for that to be the problem.

julienf28 Mon, 04/19/2010 - 09:47
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It might be that it can't connect to the TFTP server as the screen on the devices is "blank". But even then I would assume that there would be some default firmware version on the device that would let you know if you can or can't connect to the server.

J

Correct Answer
Rob Huffman Mon, 04/19/2010 - 10:15
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Hi Julien,


The reason the 7937 phone does not work with the 3550 is because the 3550 only supports Cisco Pre-Standard Power whereas the 7937 phone only supports IEEE 802.3af power


PoE power snapshot


http://www.cisco.com/warp/public/cc/pd/si/casi/ca6000/prodlit/psnap_br.pdf


7937 Data Sheet


http://www.cisco.com/en/US/prod/collateral/voicesw/ps6788/phones/ps379/ps8759/product_data_sheet0900aecd806e021a.html



Cheers!

Rob



Please support CSC Helps Haiti


https://supportforums.cisco.com/docs/DOC-8895


https://supportforums.cisco.com/docs/DOC-8727

julienf28 Mon, 04/19/2010 - 10:31
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Of course, It is good that we are changing our infrastructure from 3500 to 3750 and 2975. Thanks for the info Rob

Rob Huffman Mon, 04/19/2010 - 10:39
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Hi Julien,


You are most welcome my friend


Cheers!

Rob

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