ESXi 5.1 constantly 'not responding' in vCenter

[tinchito7]

Hi all,

I have this annoying ESXi 5.1 server that's causing me problems..

It used to be an ESX 3.5 server that I re-installed as an ESXi 5.1 yesterday.

Just to explain all the backgrounds, I've got to say that there were 2 identical servers that got through the same process (ESX 3.5 re-installed and re-configured as ESXi 5.1) -- and only one of them causes problems.

So, the problem is that this servers constantly loses network connectivity every 2 minutes or so.. and even that's not entirely correct, why?

Well, the server is connected to vCenter Server 5.1 as well, there it shows up as Not Responding. If I hit Connect from the vCenter, the servers comes back to life and is ok. For a minute or so, and then goes back to the same old status of Not Responding.

Weirdest thing is, that when the server is in that limbo situation (and I call it that because of the following), I can connect to it via SSH and even trhough vSphere Client directly.

I've ruled out an IP Conflict problem (and even tried changing the IP of the server).

The VLAN and networkiong configuration seems to be alright (though I cannot 100% rule it out because clearly it seems to be something ralated to networking).

The logs are not much of a help so far (to my naked eye).

The firmware is up to date.

And remember, there is another server, same model, same configuration, same network properties - And it works fine!

I'm clearly out of my league on this matter,

I think it might be something to do with networking configuration but I'm not expert in that field and don't know what to look for.

The only weird thing I could find is the time configuration. The BIOS time is OK but the time on the ESXi is 2 hours forward, and changing either of them simply change the other as well forward or backwards (and I can't seem to fix it).

I don't know if that got anything to do with my problem, but thought bringing that up dowsn't hurts anyone.

Help!

[lvaibhavt]

One question have you followed below article >>> I guess you might have -- just double checking !

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=100340...

[lakshya32]

Hi

Welcome to the communities.

Could you please explain little bit more like version ,tool installed etc.

And dont forget to explain HW details & log file.

"When you fail to plan, you plan to   fail."

[a_p_]

The most common cause for the behavior you describe is a DNS misconfiguration. Please double check the DNS Host-A entries for the ESXi hosts as well as vCenter Server are present and correct and ensure host in question is able to resolve the vCenter Server's FQDN (and vice versa).

André

[tinchito7]

Ok,

It is not a DNS problem because same problem occurs working with IP's..

Anyway, the vCenter Server can resolve the DNS name of the ESXi Server and establish connection.

BUT, something I havent checked before is the connection from the ESXi Server towards the VC. Bam, the host CAN resolve the DNS of the VC, BUT cannot reach it..

The main reason I didn't check this before is that I can connect the host to the VC (even if it's for a minute) so I thought ok, no problem talking to each other in this case, but clearly, it is.

I'm currently waiting for the Firewall guy here to arrive so we can check if the firewall is dropping the connection between these two.

Keep you posted.

Thanks!

[tinchito7]

Well, it seems to be that there were connection drops on the firewall side.

Damn thing..

I've would of thought that was the problem before- but what kept me confused was the fact that the server did connect to the vcenter for some time and only after got not responding status.

Thanks!!