vMotion migrations fail With a timeout error due to MTU configuration mismatch

Products

• VMware vCenter Server
• VMware Telco Cloud Platform
• VMware vSphere ESXi

Issue/Introduction

When executing a live migration, the vMotion task fails and hits a timeout threshold. The vmkernel.all logs on the source ESXi hosts explicitly record dropped packets and frame size boundary violations on the active physical uplinks:

Host: ####### (Source)

####-##-##T##:##:##.###Z cpu##:#######)Uplink: ####: vmnic#: TSO packet has large MSS (####) plus L# offset (##), which can't be fit into MTU (1500)
####-##-##T##:##:##.###Z cpu##:#######)Uplink: ####: vmnic#: TSO packet has large MSS (####) plus L# offset (##), which can't be fit into MTU (1500)
####-##-##T##:##:##.###Z cpu##:#######)Uplink: ####: vmnic#: Non TSO L# payload size exceeds uplink MTU. FrameLen: ####, L# header offset: ##
####-##-##T##:##:##.###Z cpu##:#######)Uplink: ####: vmnic#: Non TSO L# payload size exceeds uplink MTU. FrameLen: ####, L# header offset: ##
####-##-##T##:##:##.###Z cpu##:#######)Uplink: ####: vmnic#: Non TSO L# payload size exceeds uplink MTU. FrameLen: ####, L# header offset: ##

Environment

TCP: 5.0

vCenter: 7.0 U3t

ESXi: 7.0 U3s

Cause

An MTU mismatch exists across the vMotion datapath. The vMotion vmkernel interface is configured to transmit jumbo frames at MTU 9000, but the backing virtual distributed dwitch (vDS) or physical uplink infrastructure is configured with a standard MTU of 1500, causing jumbo frames to be dropped at the interface level.

Resolution

Steps:

1. Log in to the vSphere client interface.
   
   
2. Select the networking inventory tab.
   
   
3. Locate and select the affected virtual distributed switch (vDS) (e.g., ###-DVS-###-###-#).
   
   
4. Modify the properties of the vDS and change the MTU configuration value to 9000.
   
   
5. Save the configuration changes.
   
   
6. Verify that end-to-end network connectivity is functional and re-attempt the vMotion migration task.