"Host connection and power state" alarm seen on many or all hosts in vCenter

Products

• VMware vSphere ESXi

Issue/Introduction

All hosts in vCenter have an alarm triggered for "Host connection and power state":

All hosts and VMs, and vCenter itself, may be currently up and responding normally.

Environment

VMware vCenter Server (all versions)

Cause

When the vCenter VM temporarily loses connectivity, it will in turn lose connection to all hosts connected to it thereby triggering the alarm.

Resolution

If the connectivity issues occurred due to an expected reason, for example changing the vCenter VM's network, the error can be ignored.

Otherwise, the network should be investigated to determine why the vCenter lost connection temporarily.

Common reasons for intermittent vCenter connectivity are duplicate IPs or firewall blocking UDP 902 traffic between the hosts and vCenter.

See ESXi host disconnects intermittently from vCenter Server and Duplicate IP address detected.

Additional Information

Please reference the following related KBs seen in other specific conditions:

• "Host connection and power state" alarm when an ESXi host wakes from standby
• "Host connection and power state" alarm in vCenter Server due to hostd crash