NDIS QoS Traffic Classes

NDIS Quality of Service (QoS) traffic classes specify a set of policies that determine how the network adapter handles transmit, or egress, packets for prioritized delivery. Each traffic class specifies the following policies that are applied to egress packets:

Priority Level and Flow Control
This policy defines the IEEE 802.1p priority level and optional flow control algorithms for the egress traffic.

For more information, see Priority Levels and Flow Control.

Traffic Selection Algorithms (TSAs)
This policy specifies how the network adapter selects egress traffic for delivery from its transmit queues. For example, the adapter could select egress packets based on IEEE 802.1p priority or the percentage of the egress bandwidth that is allocated to each traffic class.

For more information, see Transmission Selection Algorithms (TSAs).

Note Bandwidth allocation is only supported for the Enhanced Transmission Selection (ETS) TSA. For more information, see Enhanced Transmission Selection (ETS) Algorithm.

Traffic classes are specified through object identifier (OID) method requests of OID_QOS_PARAMETERS. This OID request contains an NDIS_QOS_PARAMETERS structure that specifies the following NDIS QoS parameters:

  • The number of traffic classes to be configured on the network adapter. Each traffic class is identified by a value in the range from zero to (NumTrafficClasses–1), where NumTrafficClasses is a member of the NDIS_QOS_PARAMETERS structure.

    Note Starting with NDIS 6.30, NDIS QoS supports a maximum of NDIS_QOS_MAXIMUM_TRAFFIC_CLASSES (8) traffic classes. The network adapter must support a minimum of three traffic classes.

  • The 802.1p priority level associated with the traffic class.

  • The TSA associated with the traffic class.

  • The transmit bandwidth allocated to each traffic class that uses the ETS TSA.

OID method requests of OID_QOS_PARAMETERS also specify traffic classifications. These classifications define the relationship between egress packets and IEEE 802.1p priority levels. For more information, see NDIS QoS Traffic Classifications.