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When an IP phone is powered on, it sends out protocol packets. After receiving these protocol
packets, the device uses the source MAC address of the protocol packets to match its OUI
addresses. If the match succeeds, the system performs the following operations:
•
Assigns the receiving port of the protocol packets to the voice VLAN.
•
Issues ACL rules to set the packet precedence.
•
Starts the voice VLAN aging timer.
The system will remove the port from the voice VLAN if no packet is received from the port before the
aging timer expires. The aging timer is also configurable.
If the device reboots, the port is reassigned to the voice VLAN to ensure the correct operation of the
existing voice connections. The reassignment occurs automatically without being triggered by voice
traffic as long as the voice VLAN operates correctly.
Manual mode
Use manual mode when only IP phones access the network through the device, as shown in
. In this mode, ports are assigned to a voice VLAN that transmits voice traffic exclusively. No data
traffic affects the voice traffic transmission.
You must manually assign the receiving port on the device to a voice VLAN. The device uses the
source MAC address of the received voice packets to match its OUI addresses. If the match
succeeds, the system issues ACL rules to set the packet precedence.
To remove the port from the voice VLAN, you must manually remove it.
Cooperation of voice VLAN assignment modes and IP phones
Some IP phones send out VLAN-tagged packets, and others send out only untagged packets. For
correct packet processing, ports of different link types must meet specific configuration requirements
in different voice VLAN assignment modes.
Table 11 Configuration requirements for access/trunk/hybrid ports to support tagged voice
traffic
Port link
type
Voice VLAN
assignment mode
Support for
tagged voice
traffic
Configuration requirements
Access
Automatic No N/A
Manual No
N/A
Trunk
Automatic Yes
The PVID of the port cannot be the
voice VLAN.
Manual Yes
The PVID of the port cannot be the
voice VLAN. Configure the port to
forward the packets from the voice
VLAN.
Hybrid
Automatic Yes
The PVID of the port cannot be the
voice VLAN.
Manual Yes
The PVID of the port cannot be the
voice VLAN. Configure the port to
forward the packets from the voice
VLAN with VLAN tags.