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New Member

Voice VLAN for dummies


I present the topology and I will explain the problem.

( Internet ) < === > [ On Access Router 50 ] <==== > [ Switch SG500 - 28P ] <==== > [ SPA 514G Phone ] < ===> [ Computer ]

Each computer is connected behind a Cisco SPA514G phone which itself is connected to a switch SG500 which itself is connected to a router.
My problem is trivial, but I'm stuck . Old age probably ...

The goal is to configure my phones in VLAN 2 and my computers are in their own VLAN ( 10,20,30,40 , etc.).

I have lots of questions. I read so many thing about that and seem not working.

  • Is it better to define the VLAN (voice and datas ) directly on the phones ? or in the switch with CDP and Automatic VLAN ?
  • if not, how should we define the switch ports (access ? general ? trunk ? tagged ? untagged ?)

In short, as you can see I'm completely lost. All my tests have been failures.

The switch is in layer 2 mode not 3. The router DHCP for everyone . Also I do not think I need to level up 3 switch to make intervlan . Everything should be able to manage it at level 2. Unless I 'm wrong

Do I have to configure the automatic voice VLAN in the SG500 and do not touch the phone ?
It must configure the ports for different untagged vlan for computers and phones will fare ?
How to configure the port that will be connected to the router ?

Thank you in advance for sharing that we might have.


I have never used the SG500

I have never used the SG500 switch before but the usual approach to doing this is:

- create voice VLAN and data VLAN on switch

- configure the port that connects to the phone with the data VLAN (switchport access vlan x) and the voice vlan (switchport access voice vlan x)

- configure the port from the switch to the router as a dot1q trunk carrying voice and data VLAN

- configure the router port with dot1q tagged subinterface for each VLAN and assign layer 3 addresses

- configure relevant DHCP scopes per VLAN

That is all quite high level but if you provide a diagram and some configs it might be possible to fill in the gaps.

New Member

Thank you for your quick

Thank you for your quick responses. 

The part of the SG500 SmallBusinness range. Cisco OS inside and Linksys web interface for Dummies. Like me.smiley 

Is it really important to assign addresses block to vlan? 


You will need layer 3

You will need layer 3 addresses on the router - these will be the gateway addresses for each VLAN. Not sure if the SG500 is capable of being a DHCP server.

New Member

SG500 Can do lot of stuff. 

SG500 Can do lot of stuff.



You say you have SPA514G

You say you have SPA514G phones, do you also have an onsite PBX? Or are they using a SIP service via the internet?


What model/brand of router do you have?


And how many phones/PC's do you have?


New Member

Hello,Our phones are


Our phones are configured as SIP account directly connected to Centrex plateform.

Our ISP provide an OneAccess 50 router. Behind SDSL 4Mbs/4Mbs bandwith (up/dn)

We have 15 phones SPA504G et SPA514G (mixed).



OK so your router is probably

OK so your router is probably not going to support trunking.

You could convert your SG500 into layer 3 mode, create separate VLANs for voice and data but with you only having 15 phones I would say it’s probably not worth the trouble, you are really not going to see any improvement in performance.

New Member

Performance is not the goal

Performance is not the goal !

We have 4 differents offices on the floor. We want separate IT space virtualy.

We will use the QoS for the voice VLAN. May be...

New Member

OnAccess 50 Router support

OnAccess 50 Router support VLAN tagged and untagged like commercial datasheet said.

As mentioned already, in

As mentioned already, in order to have two Vlans (Data and Voice) you will need a Layer 3 device.

You can either configure the Router to have two LAN subnets (either using Vlan interfaces or Subinterfaces on the physical port) or you can convert the SG300 to be Layer 3 and create the VLAN Interfaces on this. Depending on the model of router you have, the latter may be your only (or easiest) option.

Unfortunately (in my opinion) the GUI used in the SG series of switches is hideous but I am a command line person so that's probably why I hate it :).

Anyway, one you have Two Vlans and routing between them working, you then need to use the GUI assign both Vlans to each port. The Data Vlan is going to be 'Untagged' because the PC's will not be capable of tagging frames so they will send their frames untagged and the switchport will tag them with the Data VLAN ID. The Voice vlan will need to be 'tagged' on each port which instructs the port to expect tagged frames from the Phones with the Voice VLAN ID.

There is a post which shows the commands with the CLI on the SG switches:

Failing that, you may need to RTFM for the SG switches :)