Users Guide

● When Peer sends a PFC message for Priority 2, based on above PRIO2COS table (TABLE 2), Queue 1Queue 2 is halted.
● Queue 1Queue 2 starts buffering the packets with Dot1p 2. This causes PG6 buffer counter to increase on the ingress, since
P-dot1p 2 is mapped to PG6.
● As the PG6 watermark threshold is reached, PFC generates for dot1p 2.
Configuration Example for DSCP and PFC Priorities
Consider a scenario in which the following DSCP and PFC priorities are necessary:
DSCP 0 – 5, 10 - 15 20 – 25, 30 – 35
Expected PFC
Priority
1 2
To configure the aforementioned DSCP and PFC priority values, perform the following tasks:
1. Create class-maps to group the DSCP subsets
class-map match-any dscp-pfc-1
match ip dscp 0-5,10-15
!
class-map match-any dscp-pfc-2
match ip dscp 20-25,30-35
2. Associate above class-maps to Queues Queue assignment as below.
Table 23. Queue Assignments
Internal-priority Queue
0 0
1 0
2 0
3 1
4 2
5 3
6 3
7 3
DellEMC(conf)#do show qos dot1p-queue-mapping
Dot1p Priority : 0 1 2 3 4 5 6 7
Queue : 1 0 2 3 4 5 6 7
3. Dot1p->Queue Mapping Configuration is retained at the default value.
4. Interface Configurations on server connected ports.
a. Enable DCB globally.
DellEMC(conf)#dcb enable
b. Apply PFC Priority configuration. Configure priorities on which PFC is enabled.
DellEMC(conf-if-tf-1/1)#pfc priority 1,2
262
Data Center Bridging (DCB)