Users Guide

Table Of Contents
752 VLANs
The Voice VLAN feature can be enabled on a per-port basis. Voice VLAN
supports a configurable Voice VLAN DSCP or IEEE 802.1p value. This value
is transmitted by LLDP when the LLDPDU is transmitted, if LLDP has been
enabled on the port, the DSCP/802.1p value is configured, and the LLDP
network policy TLV has not been suppressed for the port. LLDP-MED is
enabled by default on all ports.
Voice VLAN is supported on ports configured in access mode or in general
mode. Both multi-domain and multi-domain-multi-host authentication is
supported on ports configured for Voice VLAN in switchport general or access
mode. Only auto mode authentication is supported for Voice VLAN-enabled
ports configured in access mode. A single voice device can authenticate into
the Voice VLAN when the port is configured in access mode. Additional voice
device authentications are ignored. Voice VLAN is not supported on trunk
mode ports, although a trunk mode port may be a member of the Voice
VLAN.
Identifying Voice Traffic
Voice VLAN operates in both multi-domain and multi-domain-multi-host
host modes. In both modes, voice packets are identified by the VoIP device
source MAC address. Both multi-domain and multi-domain-multi-host
support a single VoIP device.
Voice VLAN is supported on ports configured in access mode and in general
mode. Voice VLAN is not supported on trunk mode ports, although a trunk
mode port may be a member of the Voice VLAN.
Authentication of Voice Devices
Switch ports can be configured to use either IEEE 802.1X or MAB
authentication. In both cases, the voice device must be authenticated into
the configured Voice VLAN by the RADIUS server sending an Access-Accept
message indicating the device is a voice device. If the switchport voice vlan
override-authentication option is configured, any device may access the Voice
VLAN regardless of the 802.1X port authentication state.
NOTE: Voice VLAN must be configured on general or access mode ports. It is not
supported on trunk mode ports.