Concept Guide

QoS dot1p Trac Classication and Queue
Assignment
The following section describes QoS dot1P trac classication and assignments.
DCB supports PFC, ETS, and DCBx to handle converged Ethernet trac that is assigned to an egress queue according to the following
QoS methods:
Honor dot1p You can honor dot1p priorities in ingress trac at the port or global switch level (refer to Default dot1p to Queue
Mapping) using the service-class dynamic dot1p command in INTERFACE conguration mode.
Layer 2 class maps You can use dot1p priorities to classify trac in a class map and apply a service policy to an ingress port to map
trac to egress queues.
NOTE: Dell EMC Networking does not recommend mapping all ingress trac to a single queue when using PFC and ETS.
However, Dell EMC Networking does recommend using Ingress trac classication using the service-class dynamic
dot1p command (honor dot1p) on all DCB-enabled interfaces. If you use L2 class maps to map dot1p priority trac to egress
queues, take into account the default dot1p-queue assignments in the following table and the maximum number of two lossless
queues supported on a port
(refer to Conguring Lossless Queues).
Although Dell EMC Networking OS allows you to change the default dot1p priority-queue assignments (refer to Setting dot1p Priorities
for Incoming Trac), DCB policies applied to an interface may become invalid if you recongure dot1p-queue mapping. If the
congured DCB policy remains valid, the change in the dot1p-queue assignment is allowed.
NOTE: Although, each port on the S4810, S4820T, and S5000 devices support 8 QoS queues, you can congure only 4 QoS
queues (0-3) to manage data trac. The remaining 4 queues (4-7) are reserved for control trac.
dot1p Value in
the Incoming
Frame
Egress Queue Assignment
0 0
1 0
2 0
3 1
4 2
5 3
6 3
7 3
dot1p Value in
the Incoming
Frame
Egress Queue Assignment
0 2
1 0
2 1
3 3
4 4
5 5
316 Data Center Bridging (DCB)