H3C Technologies H3C S5560 Series Switches - Manual (Page 205)

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Configuring a voice VLAN on a port
Voice VLAN assignment modes
A port can be assigned to a voice VLAN automatically or manually.
Automatic mode
Use automatic mode when PCs and IP phones are connected in series to access the network through the
device, as shown in
Figure 52 . Ports on the device transmit both voice traffic and data traffic.
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 Figure 53 .
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 13 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.