vm/vmknic traffic disconnects with software vlan untagging mode disabled with Broadcom BCM5741x NIC

Products

• VMware vSphere ESXi

Issue/Introduction

• vm/vmknic traffic disconnects with software vlan untagging mode disabled. (It is disabled by default)

• The issue happens only with Broadcom BCM5741x NIC and Dell Firmware

• After upgrade network traffic is lost 

Cause

There is an issue with the firmware programming of the CFA table entries when an interface is put in promiscuous mode. This is causing the tagged unicast traffic to get dropped.

Resolution

Please work with the hardware vendor to upgrade firmware to the fixed release.

Workaround:

To workaround the issue, please enable software VLAN untagging with the following command:

esxcli network nic software set --untagging=1 -n vmnicN

To disable software VLAN untagging: 

esxcli network nic software set --untagging=0 -n vmnicN

Additional Information

Product versions:

Broadcom BCM5741x and Dell NIC FW 229.x or earlier.

If traffic is getting dropped and the hardware/firmware is not from Dell, see: VMs experience full or partial loss of network connectivity on ESXi hosts using certain versions of bnxtnet drivers