Administrator Guide

trust diffserv
Honoring dot1p Values on Ingress Packets
The Dell Networking OS honors dot1p values on ingress packets with the Trust dot1p feature.
The following table specifies the queue to which the classified traffic is sent based on the dot1p value.
Table 54. Default dot1p to Queue Mapping
dot1p Queue ID
0 0
1 0
2 0
3 1
4 2
5 3
6 3
7 3
The dot1p value is also honored for frames on the default VLAN. For more information, refer to
Priority-Tagged Frames on the Default VLAN.
• Enable the trust dot1p feature.
POLICY-MAP-IN mode
trust dot1p
Enabling Fall Back to Trust Diffserve or dot1p
When using QoS service policies with multiple class maps, you can configure the Dell Networking OS to use
the incoming DSCP or dot1p marking as a secondary option for packet queuing if no match occurs in the
class maps.
When you use class-maps, traffic is matched against each class-map sequentially from first to last. The
sequence is based on the priority of the rules, as follows:
1 Rules with lowest priority, or in the absence of a priority configuration.
2 Rules of the next numerically higher queue.
By default, if no match occurs, the packet is queued to the default queue, Queue 0.
In the following configuration, packets are classified to queues using three class maps:
Example of Viewing Packet Classes Based on DSCP Value
!
policy-map-input input-policy
service-queue 1 class-map qos-BE1
service-queue 3 class-map qos-AF3
service-queue 4 class-map qos-AF4
trust diffserv fallback
!
Quality of Service (QoS) 744