After Failover a traffic-forwarding workload is showing slower than expected network performance

After failing over a target VM that performs traffic-forwarding functions (its purpose is to act as a network bridge for NAT, VPN, firewall, etc.) file transfers and other network traffic moving through the Failover VM runs much slower than expected.  The Failover VM will have VMXNET3 network adapters.

Solution 1:

Note: this solution is only applicable if the VM is running a Linux OS

Set the module load time parameter for the VMXNET3 adapter to include:

disable_lro=1

Solution 2:

Note: this solution is applicable to any OS the VM is running

Edit the VM settings to use E1000 NICs instead of VMXNET3

This is a known issue, confirmed by VMWare in the following ESXi 4.1 release notes:

http://www.vmware.com/support/vsphere4/doc/vsp_esxi41_vc41_rel_notes.html