Problems changing Voice VLANS on 4510

[jamescox3]

I have a 4510r+e running 12.2(44r)SG5.

Over the past few days I have been rolling out some new Cisco 7675 VoIP phones. We have 2 voice vlans that are working fine, VLAN 20 and VLAN 21. This set is going into VLAN 21.

I have changed the port config for switchport voice VLAN 21, when I look at a show mac address-table for the port it shows that the port is still in VLAN 20. A show VLAN also shows that the port is still in VLAN 20.

Some of the trouble shooting I have tried is clearning the config on the port and adding it back, works 50% of the time. Clearing ARP and the MAC address table for the port in question. Issueing a shut/ no shut on the port.

Is it possible I have a corrupt VLAN database?

Thanks

[Gregory Snipes]

Are you running any port security? These could be registered as static MACs in your CAM table.

[jamescox3]

This is one of the few switches that we don't run port security on. All of the entries in the MAC table are dynamic.

[Gregory Snipes]

If you issue a "clear mac address-table dynamic" do these entires rebuild themselves in VLAN 20, even with the VLAN set to 21 on the port?

[Gregory Snipes]

Also, did you restart the phones after you switched the VLAN over to 21? The phones could still still think their voice VLAN is 20 and be tagging their frames for that.

[Daniel McDavid]

How are the phones determining their voice VLAN ID? Can you post a 'show run int X/X' of one of the access ports in questions?