Frequent vSAN alerts: 'vMotion: Basic (unicast) connectivity check and vMotion: MTU check (ping with large packet size"

Products

• VMware vSphere ESXi

Issue/Introduction

• vSAN cluster skyline health may report frequent alerts on UI as vMotion: Basic (unicast) connectivity check and vMotion: MTU check (ping with large packet size.

• The vMotion between the hosts works fine and able to ping all the hosts vMotion vmkernel ports using vmkping command with both the MTU.

Environment

VMware vSAN 7.x

VMware vSAN 8.x

Cause

• The issue is seen where there is a response issue with the neighbor hosts on vMotion vmkernel due to underlying physical network.

• When you perform a packet capture and check for the events, you may see the events as below.

35 2.706634 10.2x.xx.10 10.2x.xx.15 ICMP 106 ✓ Echo (ping) request id=0xea5b, seq=768/3, ttl=64 (no response found!)
36 2.714445 10.2x.xx.10 10.2x.xx.12 ICMP 106 ✓ Echo (ping) request id=0xea5b, seq=768/3, ttl=64 (no response found!)
37 2.715298 10.2x.xx.10 10.2x.xx.14 ICMP 106 ✓ Echo (ping) request id=0xea5b, seq=768/3, ttl=64 (no response found!)

Resolution

This needs investigation from Physical/External network engineer. Please work with internal/physical network team.