Boot Service Discovery Protocol
Boot Service Discovery Protocol (BSDP) is an Apple-developed, standards-conforming extension of DHCP. It allows Macintosh computers to boot from bootable images on a network instead of local storage media such as CD, DVD, or hard disk. The DHCP options used are the "vendor-specific information" option (number 43) and the "vendor class identifier" option (number 60).
Source: Wikipedia — Boot Service Discovery Protocol (CC BY-SA 4.0)