unique problem. cp7911 flapping between data and voice vlan

Unanswered Question
Feb 18th, 2009

have multiple CP7911s flapping between the data ahd voice vlan both when idle and during a call.

-Setup-

UCM 6.1(2)

Cat3750

CP7911

-Port Config Looks Like-

switchport access vlan 4

switchport voice vlan 512

Have upgraded and downgraded switch firmware. Have upgraded and downgraded phone firmware.

Phone log shows the following.

NOT 08:47:24.959415 CDP-D: vvlan changed --> New:4096 old:512 4096

NOT 08:47:24.964826 CDP-D: vlan Configured --> New:4096 old:4 :4096

NOT 08:47:25.008963 CDP-D: vvlan changed --> New:512 old:4096 512

NOT 08:47:25.014483 CDP-D: vlan Configured --> New:4 old:4096 :4

NOT 09:01:24.959628 CDP-D: vvlan changed --> New:4096 old:512 4096

NOT 09:01:24.965456 CDP-D: vlan Configured --> New:4096 old:4 :4096

Anyone have any ideas what may be causing this.

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Giuseppe Larosa Wed, 02/18/2009 - 13:49

Hello Lupe,

it looks like CDP communication is not working well.

To be noted that vlan 4096 as vlan 0 cannot be used for real switch ports they are reserved for internal use in switch.

You can see a circular sequence involving vlans 4, 512 and this 4096.

Also CDP messages are sent every 60 seconds but the first log lines are very close:

NOT 08:47:24.959415 CDP-D: vvlan changed --> New:4096 old:512 4096

NOT 08:47:24.964826 CDP-D: vlan Configured --> New:4096 old:4 :4096

NOT 08:47:25.008963 CDP-D: vvlan changed --> New:512 old:4096 512

NOT 08:47:25.014483 CDP-D: vlan Configured --> New:4 old:4096 :4

I would try to span the switch port to a port with a sniffer like wireshark to see the CDP messages sent by the switch

Hope to help

Giuseppe

lupemacias Wed, 02/18/2009 - 15:28

I did that to see if I saw anything weird, but I didn't think to look for CDP messages in the capture. I'll do it again and look for CDP.

Weird thing is I don't change CDP settings. All CDP settings are default.

Thanks.

lupemacias Thu, 02/19/2009 - 17:03

after speaking with TAC, this turned out to be a bug in the cp7911 & cp7931 firmware.

CSCsu47079

TAC hooked me up with SCCP_7911_7906_8-4-3ES4 firmware for the 7911. it's looking good so far. a workaround was to reduce CDP timer to 15.

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