vCenter & Distributed vSwitch on two ESXi hosts with a single NIC

I was doing some lab work the other day with two IBM Flex nodes that only had a single 10Gb NIC.

The vCenter for the environment was located on the afformentioned ESXi hosts and my plan was to use the Distributed vSwitch, rather than the Simple vSwitch.

If you ever tried moving a ESXi host to a Distributed vSwitch which hosts the vCenter, it easy when you have more than one NIC. Just move one of the NIC’s to the Distributed vSwitch,  and then change the network configuration for the vCenter.

But when you are trying to move a ESXi host with a single NIC (whitebox, demo equipment, etc) things get a little bit more complicated.

When you attempt to move the vCenter and the ESXi host to a new Distributed Portgroup, the vCenter loses its connection and the process is rolled back. But you are still stuck with the NIC on the Simple vSwitch. Status quo…

The best way to make this work is to:

  1. Move the ESXi host that doesn’t run the vCenter VM hto the Distributed vSwitch. Create VM traffic portgroups.
  2. Clone the vCenter VM and place it on the ESXi host that doesn’t run the vCenter VM.
  3. Connect the newly cloned vCenter VM to a Distributed Portgroup on the ESXi host (that was connected to the DVS previously)
  4. Turn off the original vCenter.
  5. Turn on the cloned vCenter and configure the network settings (accept the error about a previous network using the IP if using Microsoft Server)
  6. Move the existing host to the Distributed switch.

Now you have a working vCenter on hosts with single NICs with  a Distributed vSwitch.

5 thoughts on “vCenter & Distributed vSwitch on two ESXi hosts with a single NIC”

  1. This is exactly the same problem that we are experiencing, on the same kit it seems.. (IBM PureFlex with only one 10Gb nic licensed per blade) I will be sure to give this a try when we are back in the datacenter on Monday.. thinking of getting the additional ports licensed on the chassis in any case.

    Thanks for the info!

  2. Thanks for the info – I just used the technique to move my home lab (2 x Intel NUC) to DvS.

    Some things I encountered:

    If you’re using the VCSA for your vCenter, when you clone it the MAC address changes so it won’t come up properly. There’s a VMware KB article on how to work around that:

    If you’re using iSCSI-based storage, you cannot migrate a host to the DvS until you remove the vmknic from the software iSCSI adapter, which means having no iSCSI-stored VMs running on the host at the time. You can’t vMotion them as they’re on a standard vSwitch and the other host is on a DvS. Even if you leave the old std switch in place on the other host, vMotion will still abort as it sees the old portgroup as an “intranet” . So you have to shut down the VMs to move them. That’s when it becomes important to either have two DNS servers or your host names in the vCenter hosts file.

    Thanks for the technique, and I hope the above helps anyone else trying the same operation.

  3. Great article, it got me on the right track…

    So, I had the same issue with this as well. My big issue was that i only had one host that had the single network connection was also the host for the vCenter server, so this made it real tricky! This host did have an additional NIC that was not connected to anything, so I used this to help. I also am using the VCA (vCenter Appliance), so it took some finagling.

    Here’s what I did to get around this.

    1. Initialized unused NIC as using standard switch.
    2. Created new NIC on vCenter VM, assigned it to the new switch I just created on the host.
    3. Logged into VCA, created new NIC and assigned it to – See Creating second NIC on VCA for instructions.
    4, Edit /etc/hosts on VCA to make sure for the hostname of the host I am working with is in there listed at its IP address of
    5. Disconnected the host, and then reconnected it again. Make sure you are connecting to it via hostname, and not IP address – this is important to make sure the vCenter server starts using that 192.168.1 network to talk to the host.
    6. Log into vCenter and NOW performed the NIC migration into the VDS. Since the vCenter server and host shared the other link, they never lost touch with each other and they completed the migration. (This will disconnect you, it’s okay).
    7. Log back into vCenter. Disconnect the host again, and then reconnect it. You will get the nasty warning about how it was using before, and it will reconfigure stuff – that’s okay, let it do it’s thing.

    Now, viola, Everything should be working great – time to clean up the unused stuff.

    I hope this helps some folks.

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