Voice VLAN and this scenario

Unanswered Question
Feb 18th, 2007

When i tried to search about Configuring Voice VLAN, I found :

http://www.cisco.com/univercd/cc/td/doc/product/lan/cat3560/12220se/3560scg/swvoip.htm]http://www.cisco.com/univercd/cc/td/doc/product/lan/cat...e/3560scg/swvoip.htm

And

http://www.groupstudy.com/archives/ccielab/200311/msg01225.html]http://www.groupstudy.com/archives/ccielab/200311/msg01225.html

[QUOTE]

1. "switchport voice vlan <id>". This is the most common setting, the IP

phone is asked by CDP to send the packets tagged by the VLAN <id> to

distinguish from PC packets.

2. "switchport voice vlan dot1p (NOT dot1q). This is a tagged packets

with VLAN ID = 0.

3. "switchport voice vlan untagged". Although it is stated as untagged,

the packets is actually tagged with VLAN ID = 1025".

[u]In case 2 or 3[/u], I think the switch will just accept it even it is a

non-trunking port. It is because the packets is tagged with special VLAN ID.

(I would like to be confirmed if anyone know there is a document taking

about it.)

[/QUOTE]

In the above quote he has mentioned case 2 and 3, what about case 1 ?

Regards

I have this problem too.
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drolemc Fri, 02/23/2007 - 06:39

The "switchport voice vlan untagged" command does not configure anything on the switch. The "switchport voice vlan untagged" command send CDP packets to the phone and those CDP packets configure the phone.The phone is a network device independent of the switch. If you do not modify it's behavior, it will operate based on it's defaults. If the phone defaults to sending tagged traffic or was previously configured to send tagged traffic, that's what it will do unless you configure the phone to do something else.

zillah2004 Fri, 02/23/2007 - 09:17

Thanks for this input.

You have explained point 3, my question was about point one ?

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