One VM has connectivity issues

[Irv009]

Hello,

I have a server with ESXi 4.1 on it with three VMs.  For discussion purposes, I'll call them VM1, VM2 and VM3.  They are all on the same ESX switch.

This server has a financial application on VM1 and this setup was working well for about a year.  Then, all of a sudden this past week users started getting popups while running their financial apps saying things like some table couldn't be accessed or they couldn't communicate with the SQL server, etc. As far as I know, nothing new got installed, etc. this past week on this server.

I found out that when I PING from another workstation or different physical server to VM1, it loses a lot of PING packets.  There might be 20 consecutive PING replies and then five PINGs that do not reply but no set pattern.  However, when I PING VM2 and VM3 from these other workstations or other servers, they do not have any PING issues.  I have been doing extended PING for 10 to 15 minutes and only VM1 continues to have issues with the PINGs.  It is not only a PING issue as users are getting disconnected from their financial app and I cannot connect to VM1 using RDP, etc.when this happens.  So, definitely the connectivity to VM1 is being lost intermittently.

When I PING from VM2 and VM3 to VM1, no PINGs are lost.

The physical server that hosts ESXi 4.1 has two integrated NICs but only one is being used right now.  So, all VMs are physically connected to the LAN through this one NIC.

We have a newer Ethernet switch so I temporarily moved the LAN cable connected to this ESXi server to a port on the new switch and it seemed like it got much worse.  And, again only VM1 was losing PINGs.  VM2 and VM3 were fine.  I put the LAN cable back to the original switch port and it seems like it is better but worse than before I moved the LAN cable.

If someone can give me advice on how to troubleshoot this issue, I would appreciate it greatly.

Thank you very much for your help.

[athlon_crazy]

I would start to check VM1 guest os firewall first and then VMware Tools. Sometime network threat firewall can cause your VM network become intermittent. Uninstall and reinstall VMware Tools on VM1 is worth to try.

[RustyRus · Accepted solution]

First off you need to figure out what is going on....You need to isolate is this a VMWARE problem, a Server problem or a networking problem.

I would start by pinging from VM-VM....That way you are taking out any possibilities that any physical connections are stopping things from working.

NM you have already done that........Its good

Meaning that ICMP requests are good within the VSwitch. So Internal network traffic is not seeing any issues.....

So you problem is most likely going to lie on how your traffic destined for that server is being routed to that server.

I would start with

DNS. Check and see that your DNS is functioning properly and all your zones are registered. Flush DNS on servers and workstations.

Also try reconfiguring the VMswitch or connecting that server to the spare VMnic if you can to see if that clears up your problem. Also try disabling the firewall like mentioned above......

But first and foremost identify the problem and were the break is occurying. Good luck

[Irv009]

Hello,

Thank you very much for your reply.

I turned off the firewall on VM1 but the issue is still there.  I don't believe the tools are installed but is there a way to verify

if they are?

Thank you very much for your help.

Sincerely,

[Irv009]

Hello,

Thank you very much for your reply.

I've checked both DNS servers, flushed the caches, did the same for all the other servers and workstations involved.

I also set up the second NIC, configured VM1 to use that second NIC that connected to a new different physical Ethernet switch.  Re-flushed all the caches again but I still have the same symptom where only VM1 is dropping PING packets and basically becomes disconnected from the network so that the

financial app is not usable at this time.

The firewall was disabled earlier but it did not help.

Thank you very much for your help.

Sincerely,

[Irv009]

Hello,

I found other servers that are having the same issue but not all of them so I think one or more of our Ethernet switches have gone back.  I'll have to go through all of them and figure out which servers are connected to which to determine the defective ones.  But, I'm fairly confident that it's due to the Ethernet switches.

Thank you very much for your help.

Sincerely,