Administrator 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 Networking does not recommend mapping all ingress trac to a single queue when using PFC and ETS. However,
Dell 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 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.
For DCB to operate eectively, you can classify ingress trac according to its dot1p priority so that it maps to dierent data queues. The
dot1p-queue assignments used are shown in the following table.
dot1p Value in
the Incoming
Frame
Egress Queue Assignment
0 1
1 0
2 2
3 3
4 4
5 5
6 6
7 7
Dell#show qos dot1p-queue-mapping
Dot1p Priority : 0 1 2 3 4 5 6 7
Queue : 1 0 2 3 4 5 6 7
SNMP Support for PFC and Buer Statistics Tracking
Buer Statistics Tracking (BST) feature provides a mechanism to aid in Resource Monitoring and Tuning of Buer Allocation. Max Use
Count mode in Buer Statistics is supported. Max Use Count mode provides the maximum value of the counters accumulated over a
period of time.
Priority Flow Control (PFC) provides a link level ow control mechanism, which is controlled independently for each frame priority. The goal
of this mechanism is to ensure zero loss under congestion in DCB networks.
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Data Center Bridging (DCB)