3com 5500 User Manual

In automatic mode, the switch configured with voice VLAN checks the source 
MAC address of each incoming packet against the voice device vendor OUI. If a 
match is found, the switch assigns the receiving port to the voice VLAN and tags 
the packet with the voice VLAN ID automatically.

When the port joins the voice VLAN, a voice VLAN aging timer starts. If no voice 
packets have been received before the timer expires, the port leaves the voice 
VLAN.

In manual mode, you need to manually assign a port to or remove the port from 
the voice VLAN.

Figure 7   Network diagram for voice VLAN in automatic mode

 

As shown in Figure 7, PC is connected to Ethernet 1/0/1 of Switch A through IP 
phone 1, and IP phone 2 is connected to Ethernet 1/0/2 of Switch A. IP phone 1 
sends out voice traffic with the tag of the voice VLAN, while IP phone 2 sends out 
voice traffic without any VLAN tag. Configure voice VLAN to satisfy the following 
requirements:

■

VLAN 2 functions as the voice VLAN for transmitting voice traffic, and set the 
aging time of the voice VLAN to 100 minutes. VLAN 6 transmits user service 
data.

■

Ethernet 1/0/1 and Ethernet 1/0/2 can recognize voice traffic automatically. 
Service data from PC and voice traffic are assigned to different VLANs and then 
transmitted to the server and the voice gateway respectively through Switch B.

VoIP Network

PC

IP Phone1 

(Tag)

000f-e234-1234

SwitchA

SwitchB

Voice 

Gateway

Server

IP Phone2

(Untag)

Eth1/0/1

Eth1/0/2

Oui:000f-2200-0000