Duplex mismatch between SW and IP phones

Unanswered Question

I saw a lot of posta about duplex but I'm still confused...pls help

We have a few thousand 7960 phones set to Duplex and speed Auto/Auto by default and our standard switch configuration is 100/Full hardset and not AUTO negotiation (due to historical issues with auto nego)

Is there a way to bulk set all my phones to 100/Full? The only way I say is to do it from the phone manually.

Are there good docs that show that cisco recommends that you set the switch and the phone to AUTO/AUTO....?

I did see this...but this does not seem..proof-worthy



I guess based on 802.3u - setting 100/Full on the switch and Auto/Auto on the phone is a no-no...result is duplex mismatch

I don't know why Cisco doesn't have a way to easily set the phones to 100/full...

thanks in adv


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The admin guide says "On both the network port and access port, use full-duplex mode to avoid collisions."

didn't understand if it means don't use Auto or just don't use Half-duplex..

Network and Access Ports

The back of the Cisco IP Phones models 7960G and 7940G have two RJ-45 ports labelled 10/100 SW and 10/100 PC. Each port supports 10/100 Mbps half- or full-duplex connections to external devices. You can use either Category 3 or 5 cabling for 10-Mbps connections, but you must use Category 5 for 100 Mbps connections. On both the network port and access port, use full-duplex mode to avoid collisions.


Also says you can use 100/full on both or Auto on both but does not recommend Auto...##

SW Port Configuration

Speed and duplex of the switch port.

If the phone is connected to a switch, you must configure port on the switch to the same speed/duplex as the phone, or configure both to auto-negotiate.

If you change the setting of this option, you must change the PC Port Configuration option to the same setting.


toormehdi Fri, 04/17/2009 - 08:32
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Hi there,

we are running into same issue for one of the customers. Did you find any bulk tool to do this? or is there any other alternative.

Please let me know.




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