Enable Priority Flow Control

Priority flow control (PFC) extends the basic IEEE 802.3x based flow control to multiple classes (8 classes). It enables applications that require flow control to coexist on the same link with applications that can manage without flow control.

About this task

PFC defines each one of the eight different types of flows that can be subject to flow control. In the case of an Layer 2 network, PFC uses the priority bits within the VLAN tag (IEEE 802.1p) to differentiate up to eight types of flows that can be subject to flow control, each one independently.

PFC can be configured only at the interface level.

Note

Note

PFC is supported only on devices based on the XGS chipset family. For more information, see Supported Hardware.

Procedure

  1. Enter global configuration mode.
    device# configure terminal
    
  2. Enter interface configuration mode.
    device(config)# interface ethernet 0/1
    
  3. Enable PFC the CoS for the port.
    device(conf-eth-0/1)# qos flowcontrol pfc 2 tx on rx on
    
    In this example, PFC is on CoS 2.
  4. Return to privileged EXEC mode.
    device(conf-eth-0/1)# end
    
  5. Verify the configuration.
    show qos flowcontrol interface ethernet 0/1
    Interface Ethernet 0/1
    Mode PFC
    TX frames
    RX 0 frames
           TX   TX    RX   RX Output Paused
    CoS Admin Oper Admin Oper  512 BitTimes
    ---------------------------------------
      0   Off  Off   Off  Off 
      1   Off  Off   Off  Off
      2    On   On    On   On
      3   Off  Off   Off  Off
      4   Off  Off   Off  Off
      5   Off  Off   Off  Off
      6   Off  Off   Off  Off
      7   Off  Off   Off  Off
    
  6. Save the configuration.
    device# copy running-config startup-config
    

Example

This example summarizes the commands in this procedure.

device# configure terminal
device(config)# interface ethernet 0/1
device(conf-eth-0/1)# qos flowcontrol pfc 2 tx on rx on
device(conf-eth-0/1)# end
device# show qos flowcontrol interface ethernet 0/1
device# copy running-config startup-config