Deployment Guide

PFC from the peer. If a queue is congested due to packets with a specific Dot1p and PFC is enabled for that Dot1p, switch will
transit out PFC frames for that Dot1p. The packet Dot1p to Queue mapping for classification on the ingress must be same as the
mapping of Dot1p to the Queue to be halted on the egress used for PFC honoring. Dell EMC Networking OS ensures that these
mappings are identical. This section discusses the Dell EMC Networking OS configurations needed for above PFC generation
and honoring mechanism to work for the untagged packets.
PRIORITY to PG mapping (PRIO2PG) is on the ingress for each port. By default, all priorities are mapped to PG7. A priority for
which PFC has to be generated is assigned to a PG other than PG7 (say PG6) and buffer watermark is set on PG6 so as to
generate PFC.
In ingress, the buffers are accounted at per PG basis and would indicate the number of the packets that has ingress this port
PG but still queued up in egress pipeline. However, there is no direct mapping between the PG and Queue.
Packet is assigned an internal priority on the ingress pipeline based on the queue to which it is destined. This Internal-priority to
Queue mapping has been modified and enhanced as follows for the device:
Table 21. Priority to Queue Mapping
Internal-priority Queue
0 2
1 0
2 1
3 3
4 4
5 5
6 6
7 7
Default dot1p to queue configuration is as follows:
Table 22. Dot1p to Queue Mapping
Packet-Dot1p Queue
0 2
1 0
2 1
3 3
4 4
5 5
6 6
7 7
252 Data Center Bridging (DCB)