The only valid port-set ID (port-pipe number) is 0.
Dell Networking OS Behavior: If you configure PFC on a 40GbE port, count the 40GbE port as four PFC-
enabled ports in the pfc-port number you enter in the command syntax.
To achieve lossless PFC operation, the PFC port count and queue number used for the reserved buffer
size that is created must be greater than or equal to the buffer size required for PFC-enabled ports and
lossless queues on the switch.
For the PFC buffer configuration to take effect, you must reload the stack or a specified stack unit (use
the reload command at EXEC Privilege level).
If you configure the PFC buffer on all stack units, delete the startup configuration on both the master and
standby, and reload the stack, the new master (previously standby) generates the following syslog
message for each stack unit when it boots up: PFC_BUFFER_CONFIG_CHANGED is generated for
all stack units.
Priority-Based Flow Control Using Dynamic Buffer Method
In a data center network, priority-based flow control (PFC) manages large bursts of one traffic type in
multiprotocol links so that it does not affect other traffic types and no frames are lost due to congestion.
When PFC detects congestion on a queue for a specified priority, it sends a pause frame for the 802.1p
priority traffic to the transmitting device.

Pause and Resume of Traffic

The pause message is used by the sending device to inform the receiving device about a congested,
heavily-loaded traffic state that has been identified. When the interface of a sending device transmits a
pause frame, the recipient acknowledges this frame by temporarily halting the transmission of data
packets. The sending device requests the recipient to restart the transmission of data traffic when the
congestion eases and reduces. The time period that is specified in the pause frame defines the duration
for which the flow of data packets is halted. When the time period elapses, the transmission restarts.
When a device sends a pause frame to another device, the time for which the sending of packets from
the other device must be stopped is contained in the pause frame. The device that sent the pause frame
empties the buffer to be less than the threshold value and restarts the acceptance of data packets.
Dynamic ingress buffering enables the sending of pause frames at different thresholds based on the
number of ports that experience congestion at a time. This behavior impacts the total buffer size used by
a particular lossless priority on an interface. The pause and resume thresholds can also be configured
dynamically. You can configure a buffer size, pause threshold, ingress shared threshold weight, and
resume threshold to control and manage the total amount of buffers that are to be used in your network
environment.
All the PFC-related settings such as the DCB input and output policies or DCB maps are saved in the DCB
application and the Differentiated Services Manager (DSM) application. All of these configurations can be
modified only for interfaces that are enabled for DCB. The DCB buffer configurations are also saved in the
DCB and DSM databases.

Buffer Sizes for Lossless or PFC Packets

You can configure up to a maximum of 4 lossless (PFC) queues. By configuring 4 lossless queues, you
can configure 4 different priorities and assign a particular priority to each application that your network is
264 Data Center Bridging (DCB)