H3C Technologies H3C S12500 Series Switches - Manual (Page 47)

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Voice VLAN assignment modes
Introduction to voice VLAN assignment modes
A port can be assigned to a voice VLAN in one of the following modes:
• In automatic mode, the system matches the source MAC address carried in the untagged packets
sent when an IP phone is powered on against the switch’s OUI addresses. If a match is found, the
switch automatically assigns the receiving port to the voice VLAN, issues ACL rules, and configures
the packet precedence. You can configure voice VLAN aging time on the switch. The switch
removes a port from the voice VLAN if no packet is received from the port during the aging time.
Assigning/removing ports to/from a voice VLAN are automatically performed by the switch. The
automatic mode is suitable for scenarios where PCs and IP phones connected in series access the
network through the switch and ports on the switch transmit both voice traffic and data traffic at the
same time, as shown in
Figure 11 . When the voice VLAN works correctly, in case of a switch reboot,
the switch reassigns ports in automatic voice VLAN assignment mode to the voice VLAN after the
reboot, thus ensuring that existing voice connections can work correctly. In this case, port
assignment to the voice VLAN is not triggered by voice traffic streams.
Figure 11 PCs and IP phones connected in series access the network
• In manual mode, you need to manually assign an IP phone accessing port to a voice VLAN. Then,
the switch matches the source MAC addresses carried in the packets against the switch’s OUI
addresses. If a match is found, the switch issues ACL rules and configures the packet precedence.
In this mode, assigning/removing ports to/from a voice VLAN are performed manually. The
manual mode is suitable for scenarios where only IP phones access the network through the switch
and ports on the switch only transmit voice traffic, as shown in
Figure 12 . In this mode, ports
assigned to a voice VLAN transmit voice traffic exclusively, which prevents the impact of data traffic
on the transmission of voice traffic.
Figure 12 Only IP phones access the network
Both modes forward tagged packets according to their tags.