Knowledge Base

The VMware Knowledge Base provides support solutions, error messages and troubleshooting guides
 
Search the VMware Knowledge Base (KB)   View by Article ID
 

Large packet loss at the guest OS level on the VMXNET3 vNIC in ESXi 5.x / 4.x (2039495)

Symptoms

When using the VMXNET3 driver on ESXi 4.x and 5.x, you see significant packet loss during periods of very high traffic bursts.

Cause

This issue occurs when packets are dropped due to high traffic bursts.

Resolution

To resolve this issue, slowly increase both values in the guest OS.

To reduce burst traffic drops in Windows 2008 R2 Buffer Settings:
  1. Click Start > Control Panel > Device Manager.
  2. Right-click vmxnet3 and click Properties.
  3. Click the Advanced tab.
  4. Click Small Rx Buffers and increase the value. The default value is 512  and the maximum is 8192.
  5. Click Rx Ring #1 Size and increase the value. The default value is 1024 and the maximum is 4096.

Notes:

  • It is important to increase the value of Small Rx Buffers and Rx Ring #1 gradually to avoid drastically increasing the memory overhead on the host and possibly causing performance issues if resources are close to capacity.
  • If this issue occurs on only 2-3 virtual machines, set the value of Small Rx Buffers and Rx Ring #1 to the maximum value. Monitor virtual machine performance to see if this resolves the issue.
  • The Small Rx Buffers and Rx Ring #1 variables affect non-jumbo frame traffic only on the adapter.

Additional Information

This issue can affect any application that has a high number of connections with burst traffic patterns. By using Iperf, VMware has been able to replicate the packet drop behavior with a large number of consecutive clients.

Tags

Windows 2008 R2, Exchange 2010, Packet drops, Packet loss

See Also

Update History

07/29/2013 - Added notes to Resolution section.

Request a Product Feature

To request a new product feature or to provide feedback on a VMware product, please visit the Request a Product Feature page.

Feedback

  • 18 Ratings

Did this article help you?
This article resolved my issue.
This article did not resolve my issue.
This article helped but additional information was required to resolve my issue.
What can we do to improve this information? (4000 or fewer characters)
  • 18 Ratings
Actions
KB: