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BSabolik
Contributor
Contributor

2 VMHosts; Same MAC Addr on both vSwitch2

I have discovered that I have the same mac address 00:50:56:78:c7:e2 on vSwitch2 on 2 separate physical ESXi servers. How do I change one of them? vSwitch2 is using NIC teaming and therefore not choosing the NIC's address.

Thank you in advance!

Brian

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weinstein5
Immortal
Immortal

Welcome to the Forums I am a little confused - you say you have two different ESXi servers presenting a single MAC Address is this MAC address assigned to a VM or vmkernel port? You mention only a single vSwitch and that If the vSwitch is configured for NIC teaming using the IP Hash methodology then the same MAC address will show up on multiple ort on your physical Network switch - in this configuration you will need to make sure your physical witch is configured fro LACP

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BSabolik
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The same MAC address is assigned to the vmKernel of vSwitch 2 on both machines. Luckily it was just a standby backup for my 10G network. I noticed "redundant path" error messages in the event log.

What I did to get around the problem was to remove the associated ethernet cables, added a 2nd vmkernel with an ip address in a different subnet to the 2nd esxi server. Verified the MAC address was not used in any of my other vmKernels. I then removed the original vmkernel, then changed the IP address on the new kernel giving me the same ip address but with a different mac address. Reconnected the cables and tested with pings and verified paths to the datastores.

It now works fine.

Do I have to worry about a reboot re-assigning MAC addresses?

Again we are not talking about the Virtual Machines. This is strictly about the hosts. Sorry about the vagueness in my original post.

Thanks,

Brian

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Borja_Mari
Virtuoso
Virtuoso

Hi,

because the vmware assigning mac address algorithm this kind of issue is very uncommon.

Anyway the vmkernel mac address can be statically assigned to a vmkernel vmnic using this command on the unsupported esxi host text console:

vimsh hostsvc/net/vnic_set --vnic-mac=00:50:56:xx:xx:xx vmk1

Check some more information about this command here.

Hope this helps Smiley Happy



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Pablo

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BSabolik
Contributor
Contributor

Thanks for the info! My main concern is that the MAC I have now might change with a reboot since I now have different MAC addresses and everything is working fine. Do you think I'm safe now or do I need to "statically" assign the address?

I have been told by others that I should be fine now.

Regards,

Brian

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Borja_Mari
Virtuoso
Virtuoso

Hi,

it should be fine now.

Anyway it can happens again, but it is very uncommon..

You have to think about the fact vmware prevents to have duplicated mac in the same host. But as you already know, it can happens with different hosts (but i repeat again, it is very very very rare).

I really don't know any vmware administrators that set statically the MAC addresses to prevent this kind of issue.

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Pablo

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any helpful or corrrect answer. Thanks!! -

Por favor considera premiar

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------------------------------------------------------------------------------------------------- PLEASE CONSIDER AWARDING any HELPFUL or CORRECT reply. Thanks!! Por favor CONSIDERA PREMIAR cualquier respuesta ÚTIL o CORRECTA . ¡¡Muchas gracias!! VCP3, VCP4, VCP5-DCV (VCP550), vExpert 2010, 2014 BLOG: http://communities.vmware.com/blogs/VirtuallyAnITNoob
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