' vSAN: Basic (unicast) connectivity check and vSAN: MTU check (ping with large packet size)' error after adding a new host to the existing vSAN cluster.
Article ID: 397157
Updated On:
Products
Issue/Introduction
Symptoms:
After adding a new host to existing vSAN cluster, the hosts report warnings as 'vSAN: Basic (unicast) connectivity check and vSAN: MTU check (ping with large packet size)'.
vSAN health on vSAN cluster show warnings as vSAN cluster network partition.
Environment
VMware vSAN 7.x
VMware vSAN 8.x
Cause
The issue would occur, when the hosts on vSAN cluster have different network configuration across the cluster hosts.
Example: Few hosts have two vmkernel adapters with vSAN traffic and few has only one vSAN vmkernel. This can lead to a communication issues between nodes when hosts are trying to communicate on a specific adapter/network configured for the failover purpose and that configuration does not exists on other hosts.
Resolution
In order to resolve the issue, configure uniform network on all the vSAN cluster hosts and appropriate physical network cards for failover.
Refer the below articles for more information on vSAN network considerations and using multiple vmkernel adapters for vSAN traffic.
Support for multiple vmknics with vSAN
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