Migrating ESXi Management VMkernel

I have been doing a fair amount of work with NSX recently. In order to start this work we have had some environment changes to go through before achieving this. One of the changes we had to make was to the network that contains the VMkernel for host management traffic. The overall aim was to migrate the interfaces to a new management VLAN (new subnet, gateway, etc).

Here is how I managed to do it without disruption to any existing management or services running.

1) The first step was to create a portgroup on my vDS for the new Management VLAN that had been trunked to the hosts.

I would advise to configure the port group further for your environment based on VMware Network Best Practices for things like Traffic Shaping, Teaming/Failover, etc.

2) Now the port group exists, add in a new VMkernel for all of your hosts for management traffic. For me, I ended up with 3 vmks: old management (vmk0), vMotion (vmk1) and new management (vmk2).

3) From here, I put hosts into maintenance mode that I was going to reconfigure, just to be on the safe side.

4) At this point, it isn’t possible to remove the existing vmk0 because it is in use. The reason for this, is the hosts TCP/IP stack configuration has the old VMkernel gateway configured. This should be changed to the new management network gateway address on each host:

5) From here, I disconnected the hosts from vCenter.

6) I then changed the host records of my ESXi servers to the new management IP address. Allowed some propagation (in fact I checked from the vCSA appliance that it had picked up the newest record from my DNS servers).

7) Reconnect the host(s) back into vCenter.

8) It is now possible to remove the old management VMkernel adapter (vmk0 in my case).

9) I did follow through the process of rebooting my hosts before exiting maintenance mode, but I do not actually think it matters too much.

There we go! A fairly straight forward process and one that I can’t imagine many people doing. I did have a look to see if anyone else had performed a similar process but they hadn’t moved subnet and gateway. Hopefully this might help someone out there who wants to do this!

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