Can a switch generate PFC Pause?

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I want my EXOS 670 switch to generate pause frames when it receives certain traffic or when its buffer is full. currently when i send the traffic from both ends it passes by without dropping. All packets sent are received. How to make one end stop sending one the other end is sending packets? in other words how to enable PFC on switch .
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Danial Jalil

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Posted 2 years ago

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André Herkenrath, Employee

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Just an excerpt from the User Guide - You will find more infos there..

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Danial Jalil

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Thank you Andre but this only works when my end device is generating PFC pause. i want that the switch generates PFC pause in response to my flow. Is it possible?
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Henrique, Employee

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Hi Danial,

You can find more information in the GTAC article below:

https://gtacknowledge.extremenetworks.com/articles/How_To/How-to-configure-Priority-Flow-Control
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Danial Jalil

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Yes thank you! what i am doing here is attach a test center to exos on ports say 1 and 2. now i want is if port 1 and 2 sends frames simultaneously port 1 should be paused for a while. how can i do it inside the switch because both ports can have priority 3 traffic how should i pause priority 3 traffic of say port 2.
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Henrique, Employee

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Hi Danial, I haven't tried that yet, but I guess you can accomplish that with the command below:

enable flow-control tx-pause priority 3 ports 2

The default dot1p priority values are:

802.1p Priority Value            QOS Profile
             1                                      QP1             
             2                                      QP1
             3                                      QP1
             4                                      QP1
             5                                      QP1
             6                                      QP1
             7                                      QP8  
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Danial Jalil

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No i tried this but its not working. I have the two ports in a single vlan and i applied the same command but both the ends can still receive the frames..
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Henrique, Employee

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Hi Danial, did you try the same command for rx-pause as well?

Do you see any counter incrementing to the commands below?

show port 1,2 flow-control tx-pauses
show port 1,2 flow-control rx-pauses
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Danial Jalil

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there is no command for counters 
X670V-48x.1 # show port 1
  <cr>            Execute the command
  anomaly         anomaly statistics
  buffer          Show packet buffering information
  collisions      Displays collision statistics
  configuration   Display the port configuration
  congestion      Display congestion statistics
  debounce        Display amount of time to delay link down detection
  description     Displays description associated with the port
  information     Displays port information
  ip-fix          Displays IP Flow Information Export (IPFIX) statistics
  no-refresh      Page by page display without auto-refresh
  packet          histogram of packet statistics
  qosmonitor      QOS
  rate-limit      Displays rate-limit discard statistics
  rxerrors        receive error statistics
  sharing         Load sharing
  statistics      Port statistics
  transceiver     DDMI info
  txerrors        Displays transmit error statistics
  utilization     Port utilization information
  vlan            VLAN Statistics
  wred            Display WRED statistics
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Henrique, Employee

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It seems that you are using an older EXOS code.

This command was first available in EXOS 15.6.2.
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Danial Jalil

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yes, but how to check the buffers in this code?
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Danial Jalil

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Can I give a timer value for PFC inside the switch?
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Henrique, Employee

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Hi Danial, I don't see an option to configure a time value for PFC.

To have the PFC being generated by the switch, the frames with priority 3 (in your case) should be congested.

Could you please check if one of the following commands shows any increment and share the results:

show port <port_number> congestion
show port <port_number> qosmonitor
show port <port_number> qosmonitor congestion