161Step Command Remarks2. Enter Layer 2 Ethernetinterface view.interface interface-typeinterface-number N/A3. Configure the interface to trustthe QoS priority settings inincoming voice traffic, but notto modify the CoS and DSCPvalues marked for incomingtraffic of the voice VLAN.voice vlan qos trust Use either command.By default, an interface modifies the CoSvalue and the DSCP value marked for voiceVLAN traffic into 6 and 46, respectively.The voice vlan qos command and the voicevlan qos trust command can overwrite eachother, whichever is configured last.4. Configure the interface tomodify the CoS and DSCPvalues marked for incomingtraffic of the voice VLAN intospecified values.voice vlan qos cos-valuedscp-valueConfiguring a port to operate in automatic voice VLANassignment modeConfiguration restrictions and guidelines• A protocol-based VLAN on a hybrid port can process only untagged inbound packets, whereas thevoice VLAN in automatic mode on a hybrid port can process only tagged voice traffic. Do notconfigure a VLAN as both a protocol-based VLAN and a voice VLAN. For more information, see"Configuring VLANs."• Do not configure automatic voice VLAN assignment together with MSTP, because the former ismainly configured on the access side. With MSTP enabled, if a port is blocked in the MST instance(MSTI) of the target voice VLAN, the port drops the received packets, instead of delivering them tothe CPU. As a result, the receiving port will not be dynamically assigned to the correspondingVLAN.• Do not configure automatic voice VLAN assignment together with PVST, because the former ismainly configured on the access side. With PVST enabled, if the target voice VLAN is not permittedon a port, the port is placed in the blocked state and drops the received packets, instead ofdelivering them to the CPU. As a result, the receiving port will not be dynamically assigned to thecorresponding VLAN.Configuration procedureTo set a port to operate in automatic voice VLAN assignment mode:Step Command Remarks1. Enter system view. system-view N/A2. Set the voice VLAN agingtime. voice vlan aging minutesOptional.By default, the aging time of avoice VLAN is 1440 minutes.The voice VLAN aging timeconfiguration is only applicable onports in automatic voice VLANassignment mode.
