Voice Vlan and Native Vlan

Unanswered Question

Dear all,

I am now reading some information regarding the setup of Voip Phone. It mentioned that the Phone is actually a 3-ports switch:

Port 1: Connect to upstream switch

Port 2: Transfer Phone traffic

Port 3: Connect to a PC

Actually, what should i configure on the upstream switch port? Should it be a trunk port containing both the voice traffic vlan and pc data vlan?

Or something else?

Also, there is a term called 'Voice Vlan', is there any different between 'Voice vlan' and ordinary Vlan ?

Is there any special usage of 'Native' Vlan in implementing Voip?




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paolo bevilacqua Thu, 04/10/2008 - 07:56
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The switch port is configured for access but also specifying what the voice vlan is.

The voice vlan is like any other vlan except that cdp carries this information so the phone knows what vlan to use for voice.

Native simply means untagged vlan.

Thanks. That means the access port would configured as 'voice' vlan access port. Then CDP told the IP-Phone what is the voice traffic vlan.

AFter the Voip phone get the CDP and then tagged the Voice traffic as voice vlan in its internal switch, right?

While for the data port, it would then travel as native vlan (no tag), when the switch receive this native traffic, it would pass it as native also, right?

In general, native vlan is vlan1, that means the data traffic general must be in vlan1?

paolo bevilacqua Thu, 04/10/2008 - 09:02
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Yes, exactly.

Hope this helps, please rate post if it does!


How about if the PC data should be tagged as another vlan (e.g., Vlan 10)? Then I should change the native vlan to vlan 10?

But from my understanding, Native Vlan should be the same in the whole network, then I need to change the whole network native vlan? If there are different vlans should be assigned to different PCs that behind different VoIP-phone, then how to do it?

From my guessing, is it i can assign individual native vlan (vlan10) on that port (connect to voip-phone), and then keep the switch's uplink port as original native vlan (vlan1).

Therefore, PC data traffic would be untagged when entering from voip to the switch, and then tagged as vlan10 when leaving the switch to other uplink switch, right?



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