Voice VLAN Question

Unanswered Question
Sep 18th, 2008

Does the voice VLAN for the Cisco Catalyst 3560G only work with Cisco IP phones? We currently use Toshiba phone systems running through Cisco 1841 routers at the edge.

I have this problem too.
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Brandon Buffin Thu, 09/18/2008 - 12:14

In order for the phone to receive the voice vlan info from the switch, it would need to support CDP (Cisco proprietary). I don't think Toshiba phones would support CDP. That being said, it may be possible to configure the vlan info directly on the phones and use them with Cisco switches.

Hope this helps.


hypnotoad Thu, 09/18/2008 - 12:24

Check with your phone vendor to see how they recomment setting up the switch port. Third party phones typically use an 802.1Q port setup with DHCP. The phone first comes up on the native VLAN (the data VLAN in this case) and requests an IP confuguration from DHCP. The DHCP scope would include the voice VLAN information that the phone needs to operate.

I hope this helps. Again, check with Toshiba.


tom.gabriel Thu, 09/18/2008 - 13:10

The majority of our locations use a central controller that hooks to digital phones throughout the branches. The central controller uses VoIP to connect to the other locations in the phone network. Would this work the same for them?

hypnotoad Thu, 09/18/2008 - 13:21

By "digital phones" I assume these a non-VoIP phones connected to the PBX (Central Controller) via a seperate cable plant. Is this correct.

I'm having trouble interpreting the question. Can you rephrase?


tom.gabriel Thu, 09/18/2008 - 13:28

This is correct. The phones connect back to the PBX. The PBX connects to the other PBX's that we have on our WAN. I am trying to seperate my voice traffic from my data traffic. The PBX box is on the same network as the PC's and printers. I have been doing research on the voice VLAN to see if using it would work with my Toshiba phone systems. So I guess my question is, "Can I put my Toshiba phone system traffic into the voice VLAN and it work?"

hypnotoad Thu, 09/18/2008 - 13:40

Only the PBX used VoIP to communicate with other PBXs? Are any of the phones VoIP? I'm going to assume not for this response.

Yes you can place the VoIP interface of the PBX into a voice VLAN. You need to create a voice VLAN at each site. Then you need to establish VLAN to VLAN routing accross the WAN so that the PBXs can talk to each other via IP. You will need either a layer three switch for the routing or use a router with a dot1q Ethernet interface configuration.

PBX VLAN-----\ /-----PBX VLAN

\ /


/ \


Does this make sense?


ps - the Ascii diagram looked much better before posting. Copy it to notepad to view.

tom.gabriel Thu, 09/18/2008 - 13:46

Thanks. I was thinking about trying a seperate VLAN for the voice. Would all the PBX boxes be on the same VLAN or would it be a different vlan at each location?

hypnotoad Thu, 09/18/2008 - 13:50

The VLAN name and number can be different at each site but I usually try to keep them the same for sanity sake. The VLAN won't actually cross the WAN unless you enable bridging which you really do NOT want to do. You would use routing instead.

Also keep in mind that the voice and data traffic will mix while on the WAN link. It is important that you have a QoS policy to prioritize the voice traffic.



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