virtual machines running on the ESXi host can't reach each other.

[ozzproject]

Hi,

I have a weird problem.

Virtual machines running on the ESXi machine I can reach from outside (normal machine, on the same network). All the time.

But the virtual machines running on the ESXi host can't reach each other.

When I boot the machines, I can ping them at least for a short time. But then not anymore.

ESXI 6.7 U3 machine

[DCasota]

The screenshot of your ESXi vswitch config shows up a duplicate mac address 000c29ceeb5b. This causes conflicts. For vSphere 5.5 or later have a look to Duplicate MAC Addresses of Virtual Machines on the Same Network :

The target vCenter Server re-generates the MAC address of the virtual machine. The new MAC address starts with the VMware OUI 00:0c:29 and is based on the BIOS UUID of the virtual machine. The BIOS UUID of the virtual machine is calculated from the BIOS UUID of the host.

[berndweyand]

the mac addresses shown are generated by an single esxi host. vcenter generates macs with the oui 00:50:56

[ozzproject]

Yes,  This is right. It is only one esxi. No Vsphere Center

[a_p_]

So what you say is that although the VMs can be reached from the network, they can't reach each other at the same time?

I assume that you are trying this with a ping command!? What about other services/ports, e.g. RDP, SSH, Telnet, ...

Did you check whether the VMs have firewall services enabled, which block ICMP traffic from different locations?

As a side note: You shouldn't need to worry about the duplicate MAC addresses in the screenshot that you've posted. This is likely caused by an old UI bug.

André

[ozzproject]

Yes, VMs can be reached from the network, they can't reach each other at the same time.

I tried ssh, mysql, rdp. They work as desired. But only sometimes.

May be due to the fact that some of the VMs have extremely low CPU megahertz values. They jump back and forth a lot and then they are too slow?

How can avoid this?

[a_p_ · Accepted solution]

The CPU frequency shown shouldn't be related, since the connection works from externally.

Did you already check the VM's firewall settings, A/V settings, and log files to find out whether the traffic is blocked?

Are all of the VM's built using the same OS? What about a test with another OS (even with a Live image)?

André

[ozzproject]

Dear André

it seems to be a strange problem with the firewall. I disabled it, so now it's working.