32CHAPTER 4: VOICE VLAN CONFIGURATION GUIDE

Precautions

You cannot add a port operating in automatic mode to the voice VLAN

 

manually. Therefore, if you configure a VLAN as a voice VLAN and a protocol

 

VLAN at the same time, you will be unable to associate the protocol VLAN with

 

such a port. Refer to “Configuring Protocol-Based VLAN” on page 23 for

 

description on protocol VLAN.

 

You cannot set the voice VLAN as the default VLAN on a port in automatic

 

mode.

 

The switch supports only one voice VLAN.

 

You cannot enable voice VLAN on a port configured with the Link Aggregation

 

Control Protocol (LACP).

 

Only a static VLAN can be configured as a voice VLAN.

 

When the number of ACL rules applied to a port reaches the upper threshold,

 

enabling voice VLAN on the port fails. You can use the display voice vlan

 

error-infocommand to locate such ports.

 

In the voice VLAN operating in security mode, the device allows only the

 

packets whose source address matches a recognizable voice device vendor OUI

 

to pass through. All other packets, including authentication packets such as

 

802.1x authentication packets, will be dropped. Therefore, you are

 

recommended not to transmit both voice data and service data in the voice

 

VLAN. If that is needed, disable the security mode of the voice VLAN.

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3Com 5500G, 4210, 4200G manual Precautions