Concept Guide
QoS dot1p Trac Classication and Queue
Assignment
The following section describes QoS dot1P trac classication and assignments.
DCB supports PFC, ETS, and DCBx to handle converged Ethernet trac that is assigned to an egress queue according to the following
QoS methods:
Honor dot1p You can honor dot1p priorities in ingress trac at the port or global switch level (refer to Default dot1p to Queue
Mapping) using the service-class dynamic dot1p command in INTERFACE conguration mode.
Layer 2 class maps You can use dot1p priorities to classify trac in a class map and apply a service policy to an ingress port to map
trac to egress queues.
NOTE: Dell EMC Networking does not recommend mapping all ingress trac to a single queue when using PFC and ETS.
However, Dell EMC Networking does recommend using Ingress trac classication using the service-class dynamic
dot1p command (honor dot1p) on all DCB-enabled interfaces. If you use L2 class maps to map dot1p priority trac 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 Conguring Lossless Queues).
Although Dell EMC Networking OS allows you to change the default dot1p priority-queue assignments (refer to Setting dot1p Priorities
for Incoming Trac), DCB policies applied to an interface may become invalid if you recongure dot1p-queue mapping. If the
congured 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 congure only 4 QoS
queues (0-3) to manage data trac. The remaining 4 queues (4-7) are reserved for control trac.
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)