Add ESXi Host to VCenter but the Host is shown as (disconnected)

[mingle2]

We are running ESXi 5.5 and Vcenter 5.5 and I was trying to add a host and it show (disconnected) state. 

However the VMWare host is running and up and I'm able to ssh to it.  The single VM running on the VMHost is also running. 

Is there a service that is running/or not running on VMWare host that should be?

/etc/init.d/vpxa ?

[rcporto]

Your ESXi host and vCenter are on the same subnet? And your vCenter is running on Windows or it is an appliance? If running on Windows, make sure Windows firewall is disabled or allow traffic on port 902 UDP. For additional troubleshooting check the following VMware KB article: ESXi/ESX host disconnects from vCenter Server after adding or connecting it to the inventory (204063...

[mingle2]

Hi Richardson - VCenter is running on Linux as an Appliance.

[rcporto]

And what about the network, the vCSA and the ESXi hosts are on the same subnet?

[mingle2]

From the ESXi command line do you know how to get the network (Subnet mask information) wanted to confirm.

[mingle2]

Just verified that the host is on the subnet mask as another ESXi host that is connected to VCenter.

[mingle2]

Went the the troubleshooting guide and the following is working:

grep -i serverIp /etc/vmware/vpxa/vpxa.cfg

Has my VCenter Appliance IP Address.

THe port on the ESXi host am able to Telnet to port 902 so that is working on the VMWare Host Machine.

Not sure what else to check.

[mingle2]

So one issue that I didn't realize is that we had VCenter Appliance on a VMWare Server that I'm trying to add.  The VMWare host which was not connected to the hosts in our DataCenter  on VCenter Appliance IS itself running the VCenter Appliance.  So basically VCenter Appliance Runs on ServerA as a VM -> Add Host (ServerA) to VCenter Appliance shows disconnected.  I didn't set this up so not sure why this was done this way but not sure if you can add a HOst that is Hosting the VCenter Appliance.