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Voice Vlan errors

Hi, I'm relatively new to Cisco.

I have worked through the CCNA Voice manual though I don't have experience with all the practical of it yet. I have used SSH/Telnet to connect to the router and have setup AA, Dn and users on this network so far.

I'm currently having trouble after a power outage. The vlan setup configuration seems to have gone wrong.

I currently have 3 Vlans




Our server's fixed local Ip is

All computers are getting adresses in this range by Dhcp

Data Vlan seems to be unused and all Switches and Computers run via dhcp on the range

Phones are acting out. I'm getting terrible voice quality from most of them except 2. The switchboard and one of the users who don't have extension mobillity enabled and are setup in Cisco SBCA to automaticly log-on a specific phone with specified mac to a DN.

From memmory I remember that voice quality deteriorates when vlans overlap.

Cisco SBCA reports that none of my phones except these two are in the Voice Network.

As far as I understand when you assign a smartport it automaticly sets a device to operate on a specified vlan?

How can I troubleshoot this to find a solution?

Frequent Contributor

what is the platform? 2900, 3560, or 3750?

Please provide the configuration.

I can see two problems:

1. PCs are in wrong subnet. I need to know the VLAN to IP subnet mapping. Need to configure the access VLAN or native VLAN on the switchport.

2. phones experience intermittent voice quality problem. It is a little bit tough. We should check for QoS configuration and output drops and etc. A common problem is that priority queue is not configured.



your design is curious ;-) you have a vlan for switches and servers?

An idea would be to create

VLAN xx for SSH access (vlan interface on every manageable switch)

VLAN xx for Servers (with a VLAN interface on the L3 instance)

VLAN xx for CLients (with a VLAN interface on the L3 instance)

VLAN xx for Voice (with a VLAN interface on the L3 instance)

On the VLAN interface you creat an IP helper to the DHCP server and so if a client ask for a adress in the client vlan the BC is modified to a unicast and send to the server the same procedure with a phone.

On the DHCP server you must only creat 2 scopes, one for phones one for client pc.

If you have open questions, ask or search the internet there are many config templates for such things.

Greetings Martin