VM observing packet loss and host shows packets dropped on PNIC

Products

• VMware vSphere ESXi
• VMware NSX for vSphere

Issue/Introduction

• You're observing packet loss/pings dropped when running fast ping to specific VM on NSX overlay segment from the host.
  • You're using BCM5741x and BCM5751x NICs with GENEVE traffic
• The vmnic that's used as an uplink for the VM traffic on the host shows increasing packet drops.
• NIC private stats can be found in nicinfo.sh.txt in the ESXi support bundle, or by the the following command:
  • localcli --plugin-dir /usr/lib/vmware/esxcli/int networkinternal nic privstats get -n <vmnicX>
  • ./usr/lib/vmware/vm-support/bin/nicinfo.sh
• 

Cause

• There is an NIC limitation which would lead to a potential performance issue on BCM5741x and BCM5751x NICs with GENEVE traffic.
• BCM5741X adapters do not support hardware LRO if Geneve traffic is present.

Resolution

Follow KB Performance drops on BCM5741x NICs with GENEVE traffic for more information on disabling hardware LRO aborts