You would issue the client-identifier 01aa.aabb.bbcc.cc command to create a unique identifier for a Dynamic Host Configuration Protocol (DHCP) client that uses Ethernet and that has a Media Access Control (MAC) address of aaaa.bbbb.cccc. You can specify the client identifier as a seven byte hexadecimal notation or as a 27byte dotted hexadecimal notation. To use the sevenbyte version, add the twocharacter media type to the beginning of the MAC address; for Ethernet, the media type is 01. The 27byte version takes an ASCII string that contains the vendor, the MAC address, and the source interface and converts it into dotted hexadecimal.
You would not issue the hardware address command to create a unique identifier for a DHCP client. The hardware address command is used to specify the hardware address of a Bootstrap Protocol (BOOTP) client.