MAC address controls using the HMC

The HMC version 7 release 7.2.0 or later, introduces HMC controls and policies for MAC address assignment to virtual Ethernet adapters and to logical Host Ethernet Adapter (LHEA).

By using the HMC, you can perform the following tasks:
  • Specify a custom MAC address for the virtual Ethernet adapters of a logical partition.
    Note: For a virtual Ethernet adapter, the default value is the HMC-generated MAC address.
    Tip: Avoid specifying a MAC address to enable automatic generation of a MAC address.
  • Apply the following controls to MAC address overrides specified at the operating system level:
    • Allow all operating-system-defined MAC addresses
    • Deny all operating-system-defined MAC addresses
    • Specify allowable operating-system-defined MAC addresses (you can specify a maximum of four operating-system defined MAC addresses)
      Note: By default, all overrides are allowed. This is applicable to both virtual Ethernet adapters and LHEA. HEA is not supported on POWER9™ processor-based server.
  • Specify an optional initial MAC address for a virtual Ethernet adapter to replace an HMC-generated initial MAC address.
Note: The MAC address controls can be applied only when creating a logical partition, modifying a partition profile, or dynamically adding a virtual Ethernet adapter and logical Host Ethernet Adapter. You cannot dynamically modify an existing virtual Ethernet adapter or LHEA to add or change MAC controls.
The rules for custom virtual Ethernet MAC addresses are:
  • The MAC address must be 6 bytes long.
  • The bit 1 of byte 0 is reserved for Ethernet multicasting and must always be off.
  • The bit 2 of byte 0 indicates that the MAC address is a locally administered address and must always be on.