Disclosed are methods, apparatus, and systems for the interconnection of electronic system apparatus having one or more different communication protocols. A preferred embodiment is disclosed in which a single physical interface and a single protocol are used for providing an efficient and scalable interconnection between a host and operably coupled subsystem apparatus connected to the MMC. In a disclosed method, a bus is provided for coupling a system host to a plurality of system components and a Multi-Management Protocol (MMP) is employed. The Multi-Management Protocol includes a plurality of subclasses, each further including component identity information and function data. The subclasses are grouped by functionality into at least two groups comprising a standard group and an extension group. In a multi-component electronic system according to the invention, an electronic protocol packet structure includes a starting frame delimiter, a length field, a target address field, a subclass identifier, an operation identifier, a data field, and a frame check field. Disclosed preferred embodiments also include protocol conversion apparatus having a Multi-Management Controller (MMC) using a host bus for transmitting and receiving data between a host and the MMC based on a Multi-Management Protocol (MMP).