UDP packets are dropped from Linux systems using the VMXNET3 network adapter

Products

• VMware vSphere ESXi

Issue/Introduction

Symptoms:
When using the VMXNET3 adapter in a Linux guest OS on a VMware ESXi 5.0 host, you see:

• Small UDP Packets (less than 40 bytes in size) are dropped from Linux virtual machines using the VMXNET3 Network Adapter.
• Applications that utilize small UDP packets may be unable to connect to the virtual machine.

Environment

VMware vSphere ESXi 5.0

Resolution

This issue is resolved in ESXi 5.0 Patch 04, available at VMware Downloads. For more information, see VMware ESXi 5.0, Patch ESXi-5.0.0-20120904001-standard (2032591).

To work around this issue when you do not want to upgrade, change the Virtual Machine network adapter type to E1000.

To change the network adapter on a virtual machine:

1. Right-click the virtual machine and click Edit Settings.
2. Click Add.
3. Click Ethernet Adapter and click Next.
4. In the Type field, select E1000.
5. Select the desired Network Connection label.
6. Select Connect at power and click Next.
7. Click Finish, then click OK.

At this point, you may remove the old adapter and configure the new network adapter with your desired network settings:

1. Right-click the virtual machine and click Edit Settings.
2. Click the original VMXNET3 network adapter.
3. Make a note of the selected Network Connection label.
4. Click Remove.
5. Click on the new E1000 network adapter.
6. Change the Network Connection label to the value you noted in step 3.
7. Click OK.

Note: The virtual machine may require a reboot for the changes to take effect.

Note: This issue has been seen on Linux distributions that are using a VMXNET3 driver prior to version 1.1.28.0. This driver can be found in ESXi5.1GA, available at VMware Downloads.

Additional Information

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VMware ESXi 5.0, Patch ESXi-5.0.0-20120904001-standard
VMXNET3 ネットワーク アダプタを使用した Linux システムから UDP パケットがドロップされる