Cisco 350 Series Administration Manual page 309

VLAN Management
Voice VLAN
Cisco 350, 350X and 550X Series Managed Switches, Firmware Release 2.4, ver 0.4
Voice VLAN QoS
Voice VLAN can propagate the CoS/802.1p and DSCP settings by using LLDP-MED
Network policies. The LLDP-MED is set by default to response with the Voice QoS setting if
an appliance sends LLDP-MED packets. MED-supported devices must send their voice traffic
with the same CoS/802.1p and DSCP values, as received with the LLDP-MED response.
You can disable the automatic update between Voice VLAN and LLDP-MED and use your
own network policies.
Working with the OUI mode, the device can additionally configure the mapping and
remarking (CoS/802.1p) of the voice traffic based on the OUI.
By default, all interfaces are CoS/802.1p trusted. The device applies the quality of service
based on the CoS/802.1p value found in the voice stream. In Auto Voice VLAN, you can
override the value of the voice streams using advanced QoS. For Telephony OUI voice
streams, you can override the quality of service and optionally remark the 802.1p of the voice
streams by specifying the desired CoS/802.1p values and using the remarking option under
Telephony OUI.
Voice VLAN Constraints
The following constraints exist:
• Only one Voice VLAN is supported.
• A VLAN that is defined as a Voice VLAN cannot be removed
In addition the following constraints are applicable for Telephony OUI:
• The Voice VLAN cannot be Smartport enabled.
• The Voice VLAN cannot support DVA (Dynamic VLAN assignment).
• The Voice VLAN cannot be the Guest VLAN if the voice VLAN mode is OUI. If the
voice VLAN mode is Auto, then the Voice VLAN can be the Guest VLAN.
• The Voice VLAN QoS decision has priority over any other QoS decision, except for
the Policy/ACL QoS decision.
• A new VLAN ID can be configured for the Voice VLAN only if the current Voice
VLAN does not have candidate ports.
• The interface VLAN of a candidate port must be in General or Trunk mode.
• The Voice VLAN QoS is applied to candidate ports that have joined the Voice VLAN,
and to static ports.
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