PowerEdge: BCM5720 Fails to Establish Link on Network Port After Modifying Flow Control Settings

Summary: On an ESXi host, if the Flow Control setting on the BCM5720 is modified without a cable inserted, the network interface card (NIC) may fail to establish a link when a cable is later inserted. The issue does not occur if the setting is modified with a cable inserted in the NIC port. ...

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Symptoms

Reproduction steps:

  1. Confirm that the NIC remains in the down status and no cable is inserted: 
    # esxcfg-nics -l
  2. Check the flow control status: 
    # esxcli network nic pauseParams list
  3. Perform the following command to modify the flow control setting on BCM5720: 
    # esxcli network nic pauseParams set -n vmnic0 -r 0 -t 0
Note: The example disables the flow control on vmnic0.
  1. Plug in the network cable to the BCM5720 port (vmnic0). The link does not successfully come UP.

Cause

This is expected behavior.

Resolution

Dell Technologies recommends only modifying flow control settings on BCM5720 ports with network cables connected. 
If this condition has been encountered, reboot the host to recover the port. 

To modify the flow control settings on a Dell Broadcom BCM5720 NIC without a cable inserted.

Perform the following steps:

  1. Admin down the port that you want to modify the flow control first: 
    # esxcli network nic down -n vmnic0
  1. Modify the flow control setting on the port.
  2. Admin up the port after completing the flow control setting. 
    # esxcli network nic up -n vmnic0
  1. Insert the network cable into the port.

Affected Products

Broadcom NetXtreme Family of Adapters, VMware ESXi 7.x, VMware ESXi 8.x

Products

C Series, Modular Infrastructure, Rack Servers, Tower Servers, XR Servers, PowerFlex appliance R650, PowerFlex appliance R6525, PowerFlex appliance R660, PowerFlex appliance R6625, Powerflex appliance R750, PowerFlex appliance R760 , PowerFlex appliance R7625, PowerFlex appliance R640, PowerFlex appliance R740XD, PowerFlex appliance R7525, PowerFlex appliance R840 ...
Article Properties
Article Number: 000222793
Article Type: Solution
Last Modified: 13 May 2025
Version:  4
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