You must have enough media access control (MAC) addresses to assign to the number of logical domains, virtual switches, and virtual networks you are going to use. You can have the Logical Domains Manager automatically assign MAC addresses to a logical domain, a virtual network, and a virtual switch, or you can manually assign MAC addresses from your own pool of assigned MAC addresses. The ldm subcommands that set MAC addresses are add-domain, add-vsw, set-vsw, add-vnet, and set-vnet. If you do not specify a MAC address in these subcommands, the Logical Domains Manager assigns one automatically.
The advantage to having the Logical Domains Manager assign the MAC addresses is that it uses the block of MAC addresses dedicated for use with logical domains. Also, the Logical Domains Manager detects and prevents MAC address collisions with other Logical Domains Manager instances on the same subnet. This behavior frees you from having to manually manage your pool of MAC addresses.
MAC address assignment happens as soon as a logical domain is created or a network device is configured into a domain. In addition, the assignment is persistent until the device, or the logical domain itself, is removed.