In the vpxd.log file, you see entries similar to:

 

2012-04-02T13:07:49.438+02:00 [02248 info 'Default' opID=66183d64] [VpxLRO] -- BEGIN task-internal-252 -- -- vim.SessionManager.acquireSessionTicket -- 52fa8682-47e0-2566-fb05-6192cb2c22f9(5298e245-ffb6-f7f8-e8a0-dedfbe369255)
2012-04-02T13:07:49.579+02:00 [02068 info 'Default'] [VpxLRO] -- BEGIN task-internal-253 -- host-94 -- VpxdInvtHostSyncHostLRO.Synchronize --
2012-04-02T13:07:49.579+02:00 [02068 warning 'Default'] [VpxdInvtHostSyncHostLRO] Connection not alive for host host-94
2012-04-02T13:07:49.579+02:00 [02068 warning 'Default'] [VpxdInvtHost::FixNotRespondingHost] Returning false since host is already fixed!
2012-04-02T13:07:49.579+02:00 [02068 warning 'Default'] [VpxdInvtHostSyncHostLRO] Failed to fix not responding host host-94
2012-04-02T13:07:49.579+02:00 [02068 warning 'Default'] [VpxdInvtHostSyncHostLRO] Connection not alive for host host-94
2012-04-02T13:07:49.579+02:00 [02068 error 'Default'] [VpxdInvtHostSyncHostLRO] FixNotRespondingHost failed for host host-94, marking host as notResponding
2012-04-02T13:07:49.579+02:00 [02068 warning 'Default'] [VpxdMoHost] host connection state changed to [NO_RESPONSE] for host-94
2012-04-02T13:07:49.610+02:00 [02248 info 'Default' opID=66183d64] [VpxLRO] -- FINISH task-internal-252 -- -- vim.SessionManager.acquireSessionTicket -- 52fa8682-47e0-2566-fb05-6192cb2c22f9(5298e245-ffb6-f7f8-e8a0-dedfbe369255)
2012-04-02T13:07:49.719+02:00 [02068 info 'Default'] [VpxdMoHost::SetComputeCompatibilityDirty] Marked host-94 as dirty.

 

This issue may occur if heartbeat packets are not received from the host before the one minute timeout period expires. These heartbeat packets are UDP packets sent over port 902.

 

This issue may also occur when the Windows firewall is enabled and the ports are not configured.

 

Resolution

To resolve this issue, check the Windows Firewall on the vCenter Server machine. If ports are not configured, disable the Windows Firewall.

 

If ports are configured, verify if network traffic is allowed to pass from the ESXi/ESX host to the vCenter Server system, and that it is not blocking UDP port 902.

 

To perform a basic verification from the guest operating system perspective:
  1. Click Start > Run, type wf.msc, and click OK. The Windows Firewall with Advanced Security Management console appears.
  2. In the left pane, click Inbound Rules.
  3. Right-click the VMware vCenter Server -host heartbeat rule and click Properties.
  4. In the Properties dialog, click the Advanced tab.
  5. Under Profiles, ensure that the Domain option is selected.

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