Allied Telesis AT-GS950/8 - Manual (Page 102)

Chapter 7: Voice VLAN
102
Overview
The AT-GS950/8 Voice VLAN feature is specifically designed to maintain
high quality, uninterrupted voice traffic through the switch. When talking on
a voice over IP phone, a user expects to have no interruptions in the
conversation and excellent voice quality. The Voice VLAN feature can be
configured to meet these requirements.
CoS with Voice
VLAN
The Voice VLAN CoS parameter maintains the voice quality between the
ingress and egress ports of the AT-GS950/8 switch. CoS must be enabled
for the Voice VLAN CoS priority to take effect. The CoS priority level that
you configure is applied to voice traffic on all ports of the voice VLAN.
Normally, most (non-Voice) Ethernet traffic transverses the AT-GS950/8
switch through lower order egress queues. To avoid delays and
interruptions in the voice data flow, the CoS priority level assigned to the
voice VLAN should be mapped to a higher order queue and the
scheduling algorithm should be set to Strict Priority. These settings
ensure that the voice data packets are processed before other types of
data so that the voice quality is maintained as the voice data passes
through the AT-GS950/8 switch.
Note
For more information about how to configure these CoS parameters,
see “Mapping CoS Priorities to Egress Queues” on page 171 and
“Queue Scheduling Algorithm” on page 175.
Organization
Unique Identifier
(OUI)
Each IP phone manufacturer can be identified by one or more
Organization Unique Identifiers (OUIs). An OUI is three bytes long and is
usually expressed in hexadecimal format. It is imbedded into the first part
of each MAC address of an Ethernet network device. You can find the OUI
of an IP phone in the first three complete bytes of its MAC address.
Typically, you will find that all of the IP phones you are installing have the
same OUI in common.
The AT-GS950/8 switch identifies a voice data packet by comparing the
OUI information in the packet’s source MAC address with an OUI table
that you configure when you initially set up the voice VLAN. This is
important when the Auto-Detection feature for a port and is a dynamic
voice VLAN port.
Note
See “Dynamic Auto-Detection vs Static Ports” on page 103 for more
information about the Auto-Detection feature.