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The packets that come in with packet-dot1p 2 alone will use Q1 (as per dot1p to Queue classification – Table
2) on the egress port.
•
When Peer sends a PFC message for Priority 2, based on above PRIO2COS table (TABLE 2), Queue 1 is
halted.
•
Queue 1 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 will be generated 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
Expected PFC
1
Priority
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 to be based on the below table.
Table 18. o Queues Queue Assignment
Internal-
0
priority
Queue
1
3
Dot1p->Queue Mapping Configuration is retained at the default value.
Default dot1p-queue mapping is,
Dell#show qos dot1p-queue-mapping
Dot1p Priority : 0
4
Interface Configurations on server connected ports.
a
Enable DCB globally.
Dell(conf)#dcb enable
b
Apply PFC Priority configuration. Configure priorities on which PFC is enabled.
20 – 25, 30 – 35
2
1
2
0
2
1
2
3
4
Queue :2
0
1
3
3
4
3
4
5
6
7
4
5
6
7
5
6
5
6
Data Center Bridging (DCB)
7
7
315
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Troubleshooting
