In most network deployments, generated MAC addresses are appropriate. However, you might need to set a static MAC address for a virtual network adapter.

The following examples show when you might set a static MAC address.

Virtual network adapters on different physical hosts share the same subnet and are assigned the same MAC address, causing a conflict.

You want to ensure that a virtual network adapter always has the same MAC address.

By default, VMware uses the Organizationally Unique Identifier (OUI) 00:50:56 for manually generated addresses, but all unique manually generated addresses are supported.

Note

If you choose to use the VMware OUI, part of the range has been partitioned for use by vCenter Server , host physical NICs, virtual NICs, and future use.

You can set a static MAC address using the VMware OUI prefix by adding the following line to a virtual machine‘s configuration file:

ethernet<number>.address = 00:50:56:XX:YY:ZZ

In the example, <number> refers to the number of the Ethernet adapter, XX is a valid hexadecimal number between 00 and 3F, and YY and ZZ are valid hexadecimal numbers between 00 and FF. The value for XX cannot be greater than 3F to avoid conflict with MAC addresses that are generated by the VMware Workstation and VMware Server products. The maximum value for a manually generated MAC address is shown in the sample.

ethernet<number>.address = 00:50:56:3F:FF:FF

You must also set the address type in a virtual machine’s configuration file.

ethernet<number>.addressType="static"

Because ESXi virtual machines do not support arbitrary MAC addresses, you must use the example format. Choose a unique value for XX:YY:ZZ among your hard-coded addresses to avoid conflicts between the automatically assigned MAC addresses and the manually assigned ones.

It is your responsibility to to ensure that no other non-VMware devices use addresses assigned to VMware components. For example, you might have physical servers in the same subnet, which use 11:11:11:11:11:11, 22:22:22:22:22:22 as static MAC addresses. Since the physical servers do not belong to the vCenter Server inventory, vCenter Server is not able to check for address collision.