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.

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.
  • 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. You cannot dynamically modify an existing virtual Ethernet adapter 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.