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12 VOIP TRAFFIC CONFIGURATION
This chapter covers the following topics:
◆ Global Settings – Enables VOIP globally, sets the Voice VLAN, and the
aging time for attached ports.
◆ Telephony OUI List – Configures the list of phones to be treated as VOIP
devices based on the specified Organization Unit Identifier (OUI).
◆ Port Settings – Configures the way in which a port is added to the Voice
VLAN, the filtering of non-VoIP packets, the method of detecting VoIP
traffic, and the priority assigned to voice traffic.
OVERVIEW
When IP telephony is deployed in an enterprise network, it is
recommended to isolate the Voice over IP (VoIP) network traffic from other
data traffic. Traffic isolation can provide higher voice quality by preventing
excessive packet delays, packet loss, and jitter. This is best achieved by
assigning all VoIP traffic to a single Voice VLAN.
The use of a Voice VLAN has several advantages. It provides security by
isolating the VoIP traffic from other data traffic. End-to-end QoS policies
and high priority can be applied to VoIP VLAN traffic across the network,
guaranteeing the bandwidth it needs. VLAN isolation also protects against
disruptive broadcast and multicast traffic that can seriously affect voice
quality.
The switch allows you to specify a Voice VLAN for the network and set a
CoS priority for the VoIP traffic. The VoIP traffic can be detected on switch
ports by using the source MAC address of packets, or by using LLDP (IEEE
802.1AB) to discover connected VoIP devices. When VoIP traffic is detected
on a configured port, the switch automatically assigns the port as a tagged
member the Voice VLAN. Alternatively, switch ports can be manually
configured.