Cisco 500 Series Administration Manual page 283

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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 VLAN1 (the default VLAN).
• 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.
• The voice flow is accepted if the MAC address can be learned by the
Forwarding Database (FDB). (If there is no free space in FDB, no action
occurs).
Voice VLAN Workflows
The device default configuration on Auto Voice VLAN, Auto Smartports, CDP, and
LLDP cover most common voice deployment scenarios. This section describes
how to deploy voice VLAN when the default configuration does not apply.
Cisco 500 Series Stackable Managed Switch Administration Guide
VLAN Management
Voice VLAN