Unexpected Voice VLAN Traffic with Cisco Switch

[jjk3]

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