Enable Priority Flow Control

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

PFC is supported only on Extreme 8720, Extreme 8520, SLX 9250, and SLX 9150 devices. For more information, see Supported Hardware.

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
   

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