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dcb-pfc - Man Page

show / manipulate PFC (Priority-based Flow Control) settings of the DCB (Data Center Bridging) subsystem


dcb [ OPTIONS ] pfc { COMMAND | help }

dcb pfc show dev DEV [ pfc-cap ] [ prio-pfc ] [ macsec-bypass ] [ delay ] [ requests ] [ indications ]

dcb pfc set dev DEV [ prio-pfc PFC-MAP ] [ macsec-bypass { on | off } ] [ delay INTEGER ]


PFC-MAPPING := { PRIO | all }:{ on | off }

PRIO := { 0 .. 7 }


dcb pfc is used to configure Priority-based Flow Control attributes through Linux DCB (Data Center Bridging) interface. PFC permits marking flows with a certain priority as lossless, and holds related configuration, as well as PFC counters.


For read-write parameters, the following describes only the write direction, i.e. as used with the set command. For the show command, the parameter name is to be used as a simple keyword without further arguments. This instructs the tool to show the value of a given parameter. When no parameters are given, the tool shows the complete PFC configuration.


A read-only property that shows the number of traffic classes that may simultaneously support PFC.


A read-only count of the sent PFC frames per traffic class. Only shown when -s is given, or when requested explicitly.


A read-only count of the received PFC frames per traffic class. Only shown when -s is given, or when requested explicitly.

macsec-bypass { on | off }

Whether the sending station is capable of bypassing MACsec processing when MACsec is disabled.

prio-pfc PFC-MAP

PFC-MAP uses the array parameter syntax, see dcb(8) for details. Keys are priorities, values are on / off indicators of whether PFC is enabled for a given priority.


The allowance made for round-trip propagation delay of the link in bits. The value shall be 0..65535.

Example & Usage

Enable PFC on priorities 6 and 7, leaving the rest intact:

# dcb pfc set dev eth0 prio-pfc 6:on 7:on

Disable PFC of all priorities except 6 and 7, and configure delay to 4096 bits:

# dcb pfc set dev eth0 prio-pfc all:off 6:on 7:on delay 0x1000

Show what was set:

# dcb pfc show dev eth0
pfc-cap 8 macsec-bypass off delay 4096
prio-pfc 0:off 1:off 2:off 3:off 4:off 5:off 6:on 7:on

Exit Status

Exit status is 0 if command was successful or a positive integer upon failure.

See Also


Reporting Bugs

Report any bugs to the Network Developers mailing list <netdev@vger.kernel.org> where the development and maintenance is primarily done. You do not have to be subscribed to the list to send a message there.


Petr Machata <me@pmachata.org>

Referenced By


31 October 2020 iproute2 Linux