Voice vlan creates trunk?

[Jacob Berger]

have port on 2960 set as:

switchport mode access

switchport access vlan 100

switchport voice 200

connected a brand new (from box) 2960 to this port.

i expected all ports on the new switch to get dhcp IPs from the connecting ports vlan (like when i connect an unmanaged switch to such a port).

what happen was , the connected device didnt get dhcp addresses.

when i removed the "switchport voice 200" command everything started working - all devices on the new switch got dhcp from the subnet of adjacent port.

is this because the voice vlan command causes the port to become a trunk port and establish a trunk with the connecting port?

[Rasika Nayanajith]

If you are connecting a switch into antoher switch port you have to configure it as trunk port ( using "switchport mode trunk" interface CLI command ) to carry multiple vlan traffic to new switch. If you just want to carry single vlan then you can just confiure it as access vlan as you did (but without voice vlan x config on it).

"switchport voice vlan x" is only required when you connecting a VoIP phone to a switchport & PC which is connected to the phone with a different vlan to voice vlan. It is not a way to configure a trunk port, but allow two vlan traffic using access port configuration.

Below will help you to understand what happen when you configure "switchport voice vlan x" under an interface config.

http://mrncciew.com/2013/07/26/voip-phone-switchport-config/

HTH

Rasika

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