Forum Discussion
What MAC address
Create a new virtual switch and connect the management OS to it:
New-VMSwitch -Name 'Ext' -AllowManagementOS $true -NetAdapterName 'Prod'A new VMNetworkAdapter was created, get name and MAC address:
Get-VMNetworkAdapter -ManagementOS | Format-Table -Property 'Name', 'MacAddress'The MAC address is for example: 00155D05ED13 (the first three octets indicate "Microsoft").
Get MAC address pool of the Hyper-V host:
Get-VMHost | Select 'MacAddressMinimum', 'MacAddressMaximum' | Format-TableMy understanding is that this pool is used when creating VMNetworkAdapters for VMs.
What I see in my case is that the MAC address of the new VMNetworkAdapter is different from the possible pool values.
Question: From what pool are MAC addresses pulled for VMNetworkAdapters that are located in the management OS realm?
Hi, i understand your concern, but Hyper-V ensures the uniqueness of MAC addresses for the management OS. Even though you can’t directly control the generation process, it's highly unlikely that two identical servers will produce duplicate MACs, thereby avoiding network issues.
Hi, When creating a virtual switch with the -AllowManagementOS option, a VMNetworkAdapter for the management OS is generated; the assigned MAC address is not taken from the pool visible with Get-VMHost but is generated from an internal, separate pool, ensuring distinct management and preventing conflicts with VM addresses.
That was my assumption. Now, when I have 2 Hyper-V servers, and I configure them equally (vSwitch with -AllowManagementOS) it could theoretically happen that the auto-created VMNetworkAdapters have the same MAC addresses ('cause there's no way to control the mechanism how the MAC address is generated). I can imagine that a router then may have issues when seeing the same MAC addresses on both sides...
