Administrator Guide

Honor dot1p You can honor dot1p priorities in ingress traffic at the port or global switch level (refer to Default dot1p to Queue
Mapping) using the service-class dynamic dot1p command in INTERFACE configuration mode.
Layer 2 class maps You can use dot1p priorities to classify traffic in a class map and apply a service policy to an ingress port to map
traffic to egress queues.
NOTE: Dell EMC Networking does not recommend mapping all ingress traffic to a single queue when using PFC and
ETS. However, Dell EMC Networking does recommend using Ingress traffic classification using the service-class
dynamic dot1p command (honor dot1p) on all DCB-enabled interfaces. If you use L2 class maps to map dot1p priority
traffic 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 Configuring Lossless Queues).
Although Dell EMC Networking OS allows you to change the default dot1p priority-queue assignments (refer to Setting
dot1p Priorities for Incoming Traffic), DCB policies applied to an interface may become invalid if you reconfigure dot1p-
queue mapping. If the configured 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 configure only 4
QoS queues (0-3) to manage data traffic. The remaining 4 queues (4-7) are reserved for control traffic.
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
6 6
7 7
Configuring the Dynamic Buffer Method
Priority-based flow control using dynamic buffer spaces is supported on the switch.
To configure the dynamic buffer capability, perform the following steps:
1. Enable the DCB application. By default, DCB is enabled and link-level flow control is disabled on all interfaces.
CONFIGURATION mode
dcb enable
2. Configure the shared PFC buffer size and the total buffer size. A maximum of 4 lossless queues are supported.
Data Center Bridging (DCB)
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