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Unexpected Voice VLAN Traffic with Cisco Switch

Unexpected Voice VLAN Traffic with Cisco Switch

(OP)
I'm seeing some traffic from the voice VLAN when sniffing on one of my servers. Mostly broadcast, but occasionally unicast traffic between the CMs and some phones.

When I remove the "switchport voice vlan" command from the interface which is connected to the server the traffic goes away. The traffic is untagged and there isn't a phone between the server and the switch.

This is really unexpected since I didn't think the switch would send traffic from the voice VLAN only if it detected a phone via CDP and if it did send traffic I would expect it to be tagged traffic.

Any ideas on why I am seeing this traffic?

Thanks for any help,

Joe
 

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Joe Keegan - Joe@jjk3.com
SANS GSEC & GCFW
CCSE, CCNA, CCSA & Sun Certified

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