Incorrect configuration of MTU on vSwitch causes packets to drop
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Article ID: 324506
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Updated On:
Products
VMware vSphere ESXi
Issue/Introduction
If Jumbo Frames are enabled on an ESX host and VMNIC Maximum Transmission Unit (MTU) is set at MAX (9000), dropped packets are observed in vmkernel log files.
The vmkernel/vmkwarning log contains entries similar to:
This issue causes performance degradation of the vSwitch.
Environment
VMware ESX Server
Cause
Physical NIC Maximum MTU limitation based on the type of the NIC may vary. If the configured MTU value on a vSwitch is greater than the maximum MTU value supported by the up-link physical NIC card then dropped packets may occur.
Resolution
Configure the VMNIC MTU based on the manufacture supported MAXMTU. The sent packets must be within the MTU boundary. This is applicable for ESX 3.5 and later.