Virtual Machine not reachable when vMotioned to specific ESXi host

Products

• VMware vSphere ESXi

Issue/Introduction

• Some Virtual Machines (VM) are not reachable when vMotioned/migrated to a specific ESXi host, the network connection returns when the VM is migrated back to original host.
• Other VMs on the same portgroup/VLAN may or may not work when vMotioned to the impacted host.
• All impacted VMs use the same physical network card (vmnic).
• To check which vmnic the VM uses, ssh as root to the ESXi host and run 'esxtop' + 'n'
• Doing a packet capture on the vmnic, for incoming traffic destined to the impacted VM, shows no traffic entering the vmnic:

pktcap-uw --uplink vmnic3 --capture UplinkRcvKernel -o -|tcpdump-uw -enr - |grep <VM-IP>

• On the impacted host, if we down the vmnic, which the impacted VM is pinned to, it moved to another vmnic and traffic flows:

esxcli network nic down -n vmnic#

• Note: For details on enabling/disabling vmnic, see KB Setting link state up or down for a vmnic interface on ESXi

Environment

VMware vSphere ESXi 

Cause

The issue occurs when the physical networking is not configured to froward traffic to the ESXi vmnic.

Resolution

The physical networking team should be engaged to investigate why the traffic is not forwarded to the ESXi vmnic.