Dell N3200-ON Networking N-Series Switches CLI Reference Guide version 6.8.0 - Page 928

Switchport Voice VLAN Commands Dell Networking N1108EP-ON/N1500/N2200-ON/N3200-ON Series Switches Series Switches The Voice VLAN feature enables switch ports to carry voice traffic with an administrator-defined priority so as to enable prioritization of voice traffic over data traffic. Using Voice VLAN helps to ensure that the sound quality of an IP phone is protected from deterioration when the data traffic utilization on the port is high. Voice VLAN is the preferred solution for applying QoS to voice traffic in an enterprise environment. Voice VLAN scales with the number of ports and does not make significant demands on the switch CPU for classification of voice traffic. On a given port, any VLAN may be configured as a voice VLAN. The switch supports configuring multiple VLANs as voice VLANs. However, Voice VLAN does require the administrator to perform the additional configuration step of defining the QoS policy to be applied to voice traffic. The switch can be configured to support voice VLAN on a port connecting to the VoIP phone. When a VLAN is associated with a voice VLAN-enabled port, the VLAN ID information is passed onto the VoIP phone using LLDPMED. Voice data coming from the VoIP phone is tagged by the phone with the transmitted VLAN ID; regular data arriving on the switch is given the default PVID of the port. When an IEEE 802.1p priority is associated with a voice VLAN-enabled port, the priority information is passed to the VoIP phone using LLDP-MED. It is expected that the voice data coming from the VoIP phone is tagged with VLAN 0 or the voice VLAN and with the transmitted priority. Configure the voice vlan data priority on the port to enable the switch to transmit the IEEE 802.1p or DSCP values to the phone in the LLDP-MED Network Policy TLV. Regular data arriving on the switch is given the default priority of the port (default 0) and the voice traffic is received with the priority assigned by the phone, allowing the switch to provide distinguished service to the voice traffic. The switch can be configured to override the voice traffic CoS by entering an internal ACL associated with the MAC address of the IP phone. Alternatively, a diffserv policy can be configured for the voice VLAN which assigns voice traffic to a queue and also remarks the CoS or DSCP values in the voice Layer 2 Switching Commands 928