I ran into an issue the other day in a UCS blade system where all of the VMK0 had the same MAC addresses. See VMware KB https://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1031111
I had to remove the vmk0 port group (removes connectivity) and then I had to add this back through a KVM connection to the host. This is how I did it. Make sure you save the IP Information before making any changes.
VMK0 MAC Before
- Open ILO or KVM session to your host. Under troubleshooting choose the “Enable ESXi Shell” option. Once enabled do an alt-F1 on the keyboard and you should be at a login prompt. Login with root and your root password.
- I am going to use my port group name of “ESXi_MGMT” as an example. Yours might be different. Type esxcfg-vmknic -d -p ESXi_MGMT . This will remove vmk0.
- Type esxcfg-vmknic -a -I <management IP> -n <netmask> -p ESXi_MGMT. This will add the vmkernel back.
VMK0 MAC After Change
One important thing to note. Notice that Management traffic is no longer enabled on my vmk0 connection. You must edit this connection and check the box for management traffic. VMware will automatically move management to another vmk so make sure you go through and remove it from that vmkernel.