Configuring DiffServ-to-VLAN Priority Mapping

The QoS Mapping table lets you configure up to 64 DiffServ-to-VLAN priority mapping for Layer 3 and Layer-2 Quality of Service (QoS). For each packet sent to the LAN, the VLAN Priority of the packet is set according to the DiffServ value in the IP header of the packet.Layer-2 802.1Q frames have a 2-byte field called Tag Control Information. The three most significant bits of this 2-byte field represents the Class of Service (CoS) value. Layer-2 QoS is represented by this CoS value which is from 0 to 7 (thus 8 values). Layer-2 QoS parameters define the values for the 3 priority bits in the VLAN tagaccording to the value of the DiffServ field in the packet IP header (according to the IEEE 802.1p standard). Differentiated Services (DiffServ) is an architecture providing different types or levels of service for IP traffic. DiffServ (according to RFC 2474), prioritizes certain traffic types based on priority, accomplishing a higher-level QoS at the expense of other traffic types. By prioritizing packets, DiffServ routers can minimize transmission delays for time-sensitive packets such as VoIP packets.

The following procedure describes how to configure DiffServ-to-VLAN priority mapping through the Web interface. You can also configure it through ini file [DiffServToVlanPriority] or CLI (configure network > qos vlan-mapping).

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To configure DiffServ-to-VLAN priority mapping:

Open the QoS Mapping table (Setup menu > IP Network tab > Quality folder > QoS Mapping).

Click New; the following dialog box appears:

Configure a DiffServ-to-VLAN priority mapping rule according to the parameters described in the table below.

Click Apply, and then save your settings to flash memory.

QoS Mapping Table Parameter Descriptions

Parameter	Description
'Index'	Defines an index number for the new table row. Note: Each row must be configured with a unique index.
'Differentiated Services' diff-serv [DiffServToVlanPriority_DiffServ]	Defines a DiffServ value. The valid value is 0 to 63. The default is 0.
'VLAN Priority' vlan-priority [DiffServToVlanPriority_VlanPriority]	Defines the VLAN priority level. The valid value is 0 to 7. The default is 0.

Parameter

Description

'Index'

Defines an index number for the new table row.

Note: Each row must be configured with a unique index.

'Differentiated Services'

diff-serv

[DiffServToVlanPriority_DiffServ]

Defines a DiffServ value.

The valid value is 0 to 63. The default is 0.

'VLAN Priority'

vlan-priority

[DiffServToVlanPriority_VlanPriority]

Defines the VLAN priority level.

The valid value is 0 to 7. The default is 0.