Users Guide

Table Of Contents
802 VLANs
console(config-if-Gi1/0/10)#authentication port-control auto
console(config-if-Gi1/0/10)#authentication host-mode multi-
host
5
Enable the Voice VLAN feature on the interface
console(config-if-Gi1/0/10)#switchport voice vlan 25
6
Disable authentication for the Voice VLAN on the port. This step is
required only if the voice phone does not support port-based
authentication. MAB is not enabled on this port as other devices such as a
PC will still authenticate using 802.1X.
console(config-if-Gi1/0/10)#switchport voice vlan override-
authentication
7
Exit to Privileged Exec mode.
console(config-if-Gi1/0/10)#<CTRL+Z>
8
View the Voice VLAN settings for port 10.
console#show voice vlan interface gi1/0/10
Interface............................. Gi1/0/10
Voice VLAN Interface Mode............. Enabled
Voice VLAN ID......................... 25
Voice VLAN COS Override............... False
Voice VLAN DSCP Value................. 46
Voice VLAN Port Status................ Disabled
Voice VLAN Authentication............. Disabled
Enterprise Voice VLAN Configuration With QoS
In this example, Voice VLAN traffic is transmitted and received tagged on
VLAN 25 using IEEE 802.1p user priority 5. Background traffic is carried on
the default VLAN. The 802.1p user priority 5 tagged packets are mapped onto
internal CoS queue 2. CoS queue 2 is additionally configured as strict priority
to ensure that the latency-sensitive voice traffic is transmitted first. This is to
help overcome the quantization effect of IP traffic, where the first voice
sample in an IP packet is typically delayed 10 or 20 ms while the voice
samples are collected. A rate-limiting ACL is applied to ensure that 802.1p
priority 5 packets are limited in their ability to disrupt lower-priority traffic via
a denial-of-service attack.
To configure the switch on the IP phone facing interface:
1
Create the Voice VLAN.