VCF installation reports a warning during network validation.

Products

• VMware vSAN

Issue/Introduction

Symptoms :

• During the VMware Cloud Foundation (VCF) deployment process, the VCF Installer reports a warning during the network validation phase.
  ESX Host '######### -> ###.#.#.###" VLAN ###" with MTU 9000 fail to vmkping. Possible no network connection or not reachable
Remediation: Ensure that ESX Host ######### is responsive

Environment

• VMware vSAN 8.x
• VMware vSAN 9.x

Cause

The network validation fails due to underlying connectivity issues between the ESXi hosts

Cause validation:

• The /var/log/vmware/vcf/domainmanager/domainmanager.log file on the VCF installer confirms that the ping tests between the ESXi hosts with packet size 8972 failed with 100% packet loss. 
  YYYY-MM-DDTHH:MM.SSSZ+0000 DEBUG [vcf_dm,################################,####] [c.v.e.s.c.c.v.esx.EsxCommandExecutor,dm-exec-#]  #########: esxcli response:
YYYY-MM-DDTHH:MM.SSSZ+0000 DEBUG [vcf_dm,################################,####] [c.v.e.s.c.h.n.EsxiHostNetworkingUtil,dm-exec-#]  Pinged ###.#.#.### via VM Kernel vmk# with MTU 8972 from ESXi host #########: {"DataObject":[{"Summary":{"Duplicated":0,"HostAddr":"###.#.#.###","PacketLost":100,"Received":0,"Recieved":0,"RoundtripAvg":-2147483648,"RoundtripAvgMS":-2147483648,"RoundtripMax":0,"RoundtripMaxMS":0,"RoundtripMin":999999000,"RoundtripMinMS":999999,"Transmitted":3}}]}


• The /var/log/vmware/vcf/domainmanager/domainmanager.log file on the VCF installer also confirms that the ping with standard MTU 1500 (packet size 1472) also failed with 100% packet loss. 
  YYYY-MM-DDTHH:MM.SSSZ+0000 DEBUG [vcf_dm,################################,####] [c.v.e.s.v.v.SinglePortgroupValidator,dm-exec-#]  Ping with MTU 9000 failed, attempting ping with standard MTU
YYYY-MM-DDTHH:MM.SSSZ+0000 DEBUG [vcf_dm,################################,####] [c.v.e.s.c.h.n.EsxiHostNetworkingUtil,dm-exec-#]  Pinged ###.#.#.### via VM Kernel vmk# with MTU 1472 from ESXi host #########: {"DataObject":[{"Summary":{"Duplicated":0,"HostAddr":"###.#.#.###","PacketLost":100,"Received":0,"Recieved":0,"RoundtripAvg":-2147483648,"RoundtripAvgMS":-2147483648,"RoundtripMax":0,"RoundtripMaxMS":0,"RoundtripMin":999999000,"RoundtripMinMS":999999,"Transmitted":3}}]}


• Since both the pings (with packet size 1472 and 8972) failed, the validation reports warning as mentioned below.
  YYYY-MM-DDTHH:MM.SSSZ+0000 DEBUG [vcf_dm,################################,####] [c.v.e.s.c.v.util.ResponseUtil,dm-exec-4]  Build validation response: {"errorCode":"VALIDATE_ESXI_VMKPING.warning","arguments":["#########","###.#.#.###","###","9000"],"context":{"severity":"WARNING","bundleName":"com.vmware.evo.sddc.common.validation.errors.messages"},"message":"ESX Host \#########\#####-\#####\########.#.#.###\##### VLAN \#####\##### with MTU 9000 fail to vmkping. Possible no network connection or not reachable","remediationMessage":"Ensure that ESX Host ######### is responsive"}

Resolution

Engage network team to fix the communication issues between the hosts and then proceed to deploy VCF.