
174CHAPTER 13: CONFIGURING QUALITY OF SERVICE
| Defining Voice | Voice VLAN allows network administrators to enhance VoIP service by | 
| VLAN | configuring ports to carry IP voice traffic from IP phones on a specific | 
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 | VLAN. VoIP traffic has a preconfigured OUI prefix in the source MAC | 
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 | address. Network Administrators can configure VLANs on which voice IP | 
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 | traffic is forwarded.  | 
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 | auto Voice VLAN secure mode. Voice VLAN also provides QoS to VoIP, | 
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 | ensuring that the quality of voice does not deteriorate if the IP traffic is | 
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 | received unevenly. The system supports one Voice VLAN. | 
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 | There are two operational modes for IP Phones: | 
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 | ■ IP phones are configured with  | 
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 | tagged packets are used for all communications. | 
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 | ■ If the IP phone’s  | 
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 | packets. The phone uses untagged packets while retrieving the initial | 
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 | IP address through DHCP. The phone eventually use the Voice VLAN | 
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 | and start sending tagged packets. | 
This section contains the following topics:
■Viewing Voice VLANs
■Defining Voice VLAN
■Defining Voice VLAN Port Settings
■Viewing Voice VLAN Port Definitions
■Viewing the OUI Summaries
■Modifying OUI Definitions
