78XX Phone PoE problem with 6500 Switch.

[silvakizir]

Hi.

I have a 4500 Switch and a 6500 Switch.

When I plug in both 78xx and 79xx phones in the 4500 Cisco Switch they get their power through the PoE perfectly.

When I plug in 79XX phones in the 6500 Cisco Switch they also work with PoE but when I plug in the 78xx Phones in the 6500 they do not take power as I can't also see them from the switch with the command "show cdp neighbors". For the 78xx phones I need an external power in order to make them work.

Do you have any ideas as I can't find similar problem in the net.

Also it may be a switch problem so I don't know if this is the right category for my problem.

Thank you.

[Rob Huffman]

Hi there,

You may be hitting this bug;

7841 phones fail to power up and boot fully when connected to 6500 PoE

CSCuw03106

Cheers!

Rob

[silvakizir]

Dear Rob, thank you for your answer.

I've seen this bug when I was searching for a solution.

First of all the phones do not begin booting and then turn off (no power). They do not power on at all.

Second I've changed the firmware of the phones to other version apart from the 10.3.1-12 described that hit the bug.

Third I tried to change the power inline form auto to static but the Switch did not have the specific command.

Maybe because the IOS version is 12.X

Before suggesting to change the IOS of the Switch and because it will have downtime and it is not a 100% possible solution to my problem In my opinion, can you think of anything else?

Thank you.

[Leo Laohoo]

Post the complete output to the following commands: 

1. sh module; 
2. sh power in <PORT>; and
3. sh interface <PORT> cont

[silvakizir]

The problem is solved.

The module from Catalyst 6500 supports only Cisco Inline Power while the 7800 support only IEEE 802.3af

The module from Catalyst 4500 supports both Inline Power and 802.3af

7900 Phones support if not only Inline Power but also 802.3af and that is why they could work in 6500.

Thank you for your answers.