Cisco 350 Series Administration Manual page 306

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The device supports a single voice VLAN. By default, the voice VLAN is VLAN 1. The voice
VLAN is defaulted to VLAN 1. A different voice VLAN can be manually configured. It can
also be dynamically learned when Auto Voice VLAN is enabled.
Ports can be manually added to the voice VLAN by using basic VLAN configuration
described in the Configuring VLAN Interface Setting section, or by manually applying voice-
related Smartport macro to the ports. Alternatively, they can be added dynamically if the
device is in Telephony OUI mode, or has Auto Smartports enabled.
Dynamic Voice VLAN Modes
The device supports two dynamic voice VLAN modes: 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 device is in Telephony OUI mode and a port is manually configured as a
candidate to join the voice VLAN, the device 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
• 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 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.
Voice End-Points
To have a voice VLAN work properly, the voice devices, such as Cisco phones and VoIP
endpoints, must be assigned to the voice VLAN where it sends and receives its voice traffic.
Some of the possible scenarios are as follows:
• A phone/endpoint may be statically configured with the voice VLAN.
Cisco 350, 350X and 550X Series Managed Switches, Firmware Release 2.4, ver 0.4
VLAN Management
Voice VLAN
Telephony OUI.