Users Guide

Field Description
Appln Priority TLV
Pkts
QoS dot1p Trac Classication and Queue Assignment
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 dot1p priorities in ingress trac are used at the port or global switch level.
Layer 2 class maps dot1p priorities are used 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 Networking does not recommend mapping all ingress trac to a single queue when using PFC and ETS.
However, Dell 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.
Although the system allows you to change the default dot1p priority-queue assignments, DCB policies applied to an interface
may become invalid if you recongure dot1p-queue mapping. If the congured dcb-map remains valid, the change in the dot1p-
queue assignment is allowed. For DCB ETS enabled interfaces, trac destined to queue that is not mapped to any dot1p
priority are dropped.
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
Troubleshooting PFC, ETS, and DCBx Operation
In the show interfaces pfc | ets | dcbx output, the DCBx operational status may be down for any of the reasons
described in the following table.
When DCBx is down, the following values display in the show output eld for DCBx Oper status:
• PFC DCBx Oper status: Down
• ETS DCBx Oper status: Down
• DCBx Oper status: Disabled.
Reason
Description
Port Shutdown Port is shut down. All other reasons for DCBx inoperation, if any, are ignored.
Data Center Bridging (DCB)
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