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Voice Vlan on 3750

mialbert
Beginner
Beginner

I am wanting to know some information about a voice vlan configuration on the 3750 catalyst. This is a converged voip scenario where the pc’s plug into the phones and the phones into the 3750.   I have a configuration for one of the voice ports as below.  My question concerns what to do with the default vlan?  Can I make the data vlan the default vlan(thereby having no need for vlan 100).  If not, what would I do with other devices like printers and ap’s?  Would they just go into vlan 100 as well?  Or can I just make the data vlan the default vlan(vlan 1) and thereby having no need of vlan 100?

vlan 100

 name COMPUTER

 exit

 

vlan 101

 name VOIP

 exit

 

 

interface GigabitEthernet 0/1

 switchport mode access

 switchport access vlan 100

 switchport voice vlan 101

 spanning-tree portfast

1 Accepted Solution

Accepted Solutions

gwinn.joe
Beginner
Beginner

When using the Voice Vlan, the switch identifies the Cisco IP phone using CDP and puts that traffic into the Voice Vlan while "untagged" data traffic (traffic from the PC) is put into the access vlan.  If you're using a Cisco IP phone, the Voice vlan function will work as expected (other phones may require additional configuration on the phone for the dot1Q tag).  Technically, No, you do not "need" Vlan 100.  If you removed the command, "switchport access vlan 100" from the interface, the switch would still put Cisco VOIP traffic in the Voice vlan 101 and would put data traffic (untagged) into the default Vlan of Vlan 1.  From a security standpoint, it is not recommended to use the default Vlan (Vlan 1) for your production network traffic, but from a technical standpoint, it would work just fine.  For other devices like printers and AP's, if you want to separate your traffic, you could make separate Vlans for both of them, or you could put them on the same Vlan of the computers depending on the size of your broadcast domain

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3 Replies 3

BradEast1
Participant
Participant

Your configuration looks fine. It's considered best practice to use something other than the default vlan for data, which you've done with VLAN 100. Also, you can not remove VLAN1. What you do with AP's, printers, etc. is really a matter of personal preference. I find there's a fine line between segmentation and unneeded complexity.

Thanks.  So for all printers, wap's etc.. I would need to put them in access mode vlan 100 ports?

gwinn.joe
Beginner
Beginner

When using the Voice Vlan, the switch identifies the Cisco IP phone using CDP and puts that traffic into the Voice Vlan while "untagged" data traffic (traffic from the PC) is put into the access vlan.  If you're using a Cisco IP phone, the Voice vlan function will work as expected (other phones may require additional configuration on the phone for the dot1Q tag).  Technically, No, you do not "need" Vlan 100.  If you removed the command, "switchport access vlan 100" from the interface, the switch would still put Cisco VOIP traffic in the Voice vlan 101 and would put data traffic (untagged) into the default Vlan of Vlan 1.  From a security standpoint, it is not recommended to use the default Vlan (Vlan 1) for your production network traffic, but from a technical standpoint, it would work just fine.  For other devices like printers and AP's, if you want to separate your traffic, you could make separate Vlans for both of them, or you could put them on the same Vlan of the computers depending on the size of your broadcast domain

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