Warning message

  • Cisco Support Forums is in Read Only mode while the site is being migrated.
  • Cisco Support Forums is in Read Only mode while the site is being migrated.


Unanswered Question
Nov 14th, 2007
User Badges:

Hi all, can anyone tell me if I have a 2 ports on a switch, the ports are both in a voice vlan 10, and default vlan 1 which is untagged, my question is if i plug say a pc into the ports, will they see each other, and then if i remove the pc and plug a phone in, will they see each other ?, can untagged traffic see each other in the same switch if another vlan is present on the port ?

  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 4 (1 ratings)
colin.mccrory Wed, 11/14/2007 - 15:04
User Badges:

The voice vlan 10 command will allow only packets tagged on Vlan 10, such as your phone. If a PC is plugged into the port, it will put traffic onto the untagged vlan 1.

So if you plug in two PC's they will connect on vlan1. If you plug in two phones, and are using tagged packets, they will use vlan 10.

If you plug in a phone with a PC connected to it, the phone traffic will be tagged onto vlan 10, whilst the PC will connect to vlan 1.

To sum up, if you plug PC's into the switch they will all go onto vlan 1 even if you have the voice vlan 10 command present.

Hope this makes sense.

Pavel Bykov Wed, 11/14/2007 - 16:59
User Badges:
  • Silver, 250 points or more

Or in other words:

(From layer2 perspective)

PC will see PC, and Phone will see Phone.

All phones will be in VLAN 10

All PCs will be in VLAN 1

You can plug the phone, and plug PC into phone, or just pc or just phone... it will still work in this way.

Hope this helps


This Discussion