3com 5500-ei pwr Instrução De Instalação

 

1-6 

IP phones acquiring IP address and voice VLAN through manual configuration can forward only tagged 

traffic, so the matching relationship is relatively simple, as shown in 

Table 1-3 Matching relationship between port types and voice devices acquiring voice VLAN through 

manual configuration 

Access Not 

supported 

Trunk 

Supported 

Make sure the default VLAN of the port exists and is not a 
voice VLAN, and the access port permits the traffic of the 
default VLAN. 

Automatic 

Hybrid  

Supported 

Make sure the default VLAN of the port exists and is not a 
voice VLAN, and the default VLAN is in the list of the tagged 
VLANs whose traffic is permitted by the access port. 

Access  

Not supported 

Trunk 

Supported 

Make sure the default VLAN of the port exists and is not a 
voice VLAN, and the access port permits the traffic of the 
default VLAN. 

Manual 

Hybrid  

Supported 

Make sure the default VLAN of the port exists and is not a 
voice VLAN, and the default VLAN and the voice VLAN is in 
the list of the tagged VLANs whose traffic is permitted by the 
access port. 

 

The automatic mode and manual mode described earlier only apply to the process of assigning a port to 

the voice VLAN. After a port is assigned to the voice VLAN, the switch receives and forwards all voice 

VLAN-tagged traffic without matching the source MAC address of each received packet against its OUI 

list. For a port in the manual mode with the default VLAN as the voice VLAN, any untagged packet can 

be transmitted in the voice VLAN. This makes the voice VLAN vulnerable to flow attacks, because 

malicious users can create a large amount of voice VLAN-tagged packets to consume the voice VLAN 

bandwidth, affecting normal voice communication. 

H3C series switches provide the security mode for voice VLAN to address this problem. When the voice 

VLAN works in security mode, the switch checks the source MAC address of each packet to enter the 

voice VLAN and drops the packets whose source MAC addresses do not match the OUI list. However, 

checking packets occupies lots of system resources. Therefore, in a relatively safe network, you can 

configure the voice VLAN to operate in normal mode.  

The following table presents how a packet is handled when the voice VLAN is operating in security 

mode and normal mode.