RSS is disabled for the Intel ixgbe async drivers on VXLAN prepared ESXi hosts in VMware NSX for vSphere

Products

• VMware NSX

Issue/Introduction

Symptoms:

• Receive Side Scaling (RSS) in VMware NSX for vSphere is disabled for the Intel ixgbe async drivers on VXLAN prepared ESXi hosts.
• In the/var/log/boot file in the ESXi host, you see entries similar to:
  
  <YYYY-MM-DD>T<time> 513Z cpu13:33521)<6>ixgbe: Invalid Receive-Side Scaling (RSS) specified (4), using default.
  <YYYY-MM-DD>T<time> 988Z cpu13:33521)<6>ixgbe: Invalid Receive-Side Scaling (RSS) specified (4), using default.</time></time>

Environment

VMware NSX for vSphere 6.0.x
VMware NSX for vSphere 6.1.x

Resolution

When an ESXi host is prepared for VXLAN by VMware NSX for vSphere or VMware vCloud Networking and Security, an action is performed to enable RSS on the Intel ixgbe NICs. If the ixgbe driver is an async driver, then RSS will be disabled. This can result in poor network performance.

This is a known issue affecting the Intel async ixgbe drivers with ESXi host .
RSS only being enabled if the ixgbe driver is an inbox driver.

Currently, there is no resolution.

To work around this issue, enable RSS on VXLAN prepared ESXi host with the async ixgbe drivers.

To enable RSS on VXLAN prepared ESXi host wiht the async ixgbe drivers:

1. Place the ESXi host in maintenance mode.
2. Add these two lines in the /etc/rc.local.d/local.sh to edit the file. For more information, see Editing files on an ESX host using vi or nano (1020302).
   
   vmkload_mod -u ixgbe
   vmkload_mod ixgbe RSS=1,1,1,1,1,1,1,1
    
3. Save the file.
4. Restart the ESXi host.
5. Exit maintenance mode.
6. Run this command to verify RSS is enabled by monitoring the RSS queues and confirming the counters are increasing across multiple Rx queues:
   
   ethtool -S vmnicX