Dynamic Voice VLAN Modes
The switch supports two dynamic voice VLAN modes. They are Telephony OUI (Organization Unique Identifier) mode and Auto Voice VLAN mode. The two modes affect how voice VLAN and/or voice VLAN port memberships are configured. The two modes are mutually exclusive to each other.
- Telephony OUI
In Telephony OUI mode, the voice VLAN must be a manually configured VLAN, and cannot be the default VLAN.
When the switch is in Telephony OUI mode and a port is manually configured as a candidate to join the voice VLAN, the switch dynamically adds the port to the voice VLAN if it receives a packet with a source MAC address matching to one of the configured telephony OUIs. An OUI is the first three bytes of an Ethernet MAC address. For more information about Telephony OUI, see the Configuring Telephone OUI section.
- Auto Voice VLAN
In Auto Voice VLAN mode, the voice VLAN can be either the default voice VLAN, manually configured, or learned from external devices such as UC3xx/5xx and from switches that advertise voice VLAN in CDP or VSDP. VSDP is a Cisco Small Business defined protocol for voice service discovery.
Unlike Telephony OUI mode that detects voice devices based on telephony OUI, Auto Voice VLAN mode depends on Auto Smartport to dynamically add the ports to the voice VLAN. Auto Smartport, if enabled, adds a port to the voice VLAN if it detects an attaching device to the port that advertises itself as a phone or media end points through CDP and/or LLDP-MED.