H3C Technologies H3C WX5500E Series Access Controllers - Manual (Page 162)

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QoS priority settings. You can configure the device either to modify or not to modify the QoS priority
settings that the incoming voice traffic carries.
Configuration restrictions and guidelines
Configure the QoS priority settings for voice traffic on an interface before you enable voice VLAN on the
interface. If the configuration order is reversed, your priority trust setting will fail.
After you configure a voice VLAN-enabled interface to trust the QoS priority settings in incoming voice
traffic, also use the qos trust dot1p command in interface view to configure the interface to use the
802.1p priority in incoming packets for priority mapping.
Configuration procedure
To configure QoS priority settings for voice traffic:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter Layer 2 Ethernet
interface view.
interface interface-type
interface-number
N/A
3. Configure the interface to trust
the QoS priority settings in
incoming voice traffic, but not
to modify the CoS and DSCP
values marked for incoming
traffic of the voice VLAN.
voice vlan qos trust
Use one of the commands.
By default, an interface modifies the
CoS value and the DSCP value
marked for voice VLAN traffic into 6
and 46, respectively.
The voice vlan qos command and the
voice vlan qos trust command can
overwrite each other, whichever is
configured last.
4. Configure the interface to
modify the CoS and DSCP
values marked for incoming
traffic of the voice VLAN into
specified values.
voice vlan qos cos-value
dscp-value
Configuring a port to operate in automatic voice
VLAN assignment mode
The following guidelines apply for automatic voice VLAN assignment configuration:
• Do not configure a VLAN as both a voice VLAN and a protocol-based VLAN. The voice VLAN in
automatic mode processes only tagged voice traffic, whereas a protocol-based VLAN processes
only untagged inbound packets. For more information, see " Configuring protocol-based VLANs ."
• Do not configure automatic voice VLAN assignment together with MSTP, because the former is
mainly configured on the access side. With MSTP enabled, if a port is blocked in the MST instance
(MSTI) of the target voice VLAN, the port drops the received packets, instead of delivering them to
the CPU. As a result, the receiving port will not be dynamically assigned to the corresponding
VLAN.
• Do not configure automatic voice VLAN assignment together with PVST, because the former is
mainly configured on the access side. With PVST enabled, if the target voice VLAN is not permitted
on a port, the port is placed in the blocked state and drops the received packets, instead of