I’m having an issue opening VM consoles in the vCenter client. I’m getting the error “Unable to connect to the MKS: Failed to connect to the server xxxxxxxxx:903."
I’ll give you some info on our setup.
We have 3 clusters which are based at 2 sites.
Site A is the site I’m based at and Site B is the remote site.
Site B is where our VC server is located. There are 8 hosts based at site B.
I experience the issue on random hosts on our remote site (B). A reboot resolves the issue for a time but then it occurs again. It normally only affects one host at any one time.
All the firewall settings are identical on all the hosts.
If I logon directly to our VC server which is based at the remote site and try to open a console on the same VM the problem does not occur.
I have done some reading up and many possible causes point to firewall issues. Because this is happening on random hosts and is fixed with a reboot I didn’t think this could be the issue.
A restart of the management services does not fix this. Only a reboot resolves this so far.
Hope this makes sense…
Any help would be appreciated
I would definetely rule out firewall as a culprit. Here's what you can do:
telnet on port 903 from your workstation to IP of the host on which VM with failed console resides. Run the network dump, preferrably on the gateway for esx/vcenter network and confirm that you're seeing console traffic coming from your workstation when telnetting. When the issue with console access resurfaces, telnet again (it should fail) and verify whether you're seeing incoming traffic on the same network segment your esx host is on. If no traffic is seen then firewall must be the culprit. If you can see the traffic reaching the network esx host is on but console still doesn't work, another possible problem could be IP conflict (though less likely, given that it happens on random hosts). Nonetheless, to verify whether that's the case, I would probably down the interface for management network for that host (I would also disable "Host monitoring' on the cluster beforehand) and ping host IP from another machine to see if that IP responds.
Hope that helps,
How do you access vCenter, using IP or FQDN name?
If you are accessing using IP, try with FQDN and check if the problem occurs.
This problem is mostly to do with unable to resolve DNS.
When the problem occurs try to ping the vCenter IP?