---
name: "dcb-pfc"
section: "8"
platform: "linux"
package: "iproute2"
version: "7.3.0-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/dcb-pfc"
---

# dcb-pfc(8)

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

## NAME

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

## SYNOPSIS

**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-MAP* := \[ *PFC-MAP* \] *PFC-MAPPING*

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

*PRIO* := { ***0*** .. ***7*** }

## DESCRIPTION

**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.

## PARAMETERS

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.

- **pfc-cap**

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

- **requests**

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

- **indications**

  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)](/dcb/8.md) for details. Keys are priorities, values are on / off indicators of whether PFC is enabled for a given priority.

- **delay *INTEGER***

  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

[**dcb**(8)](/dcb/8.md)

## 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.

## AUTHOR

Petr Machata \<me@pmachata.org\>