The Hardware Platform Management (HPM.x) specifications augment the Hardware Platform 
Management layer of three key PICMG platforms: AdvancedTCA (as defined by PICMG 3.0), AdvancedMC (AMC.0) and MicroTCA (MTCA.0). The foundation HPM layer for those platforms is defined by hundreds of pages in the corresponding base and subsidiary specifications. PICMG Hardware Platform Management in this broad sense is a key ingredient enabling system performance monitoring, predictive maintenance, software upgrades in live systems, and event logging. The HPM layer also enables the construction of High Availability systems, where individual subsystem failures can be detected and repaired using redundant resources.
HPM.1, the IPM Controller Firmware Upgrade specification, was adopted in 2007 and defines firmware file formats and IPMI command protocols for updating the firmware in ATCA, AMC, and MicroTCA management controllers (which are generically referenced as “HPM controllers” below).
HPM.2, the LAN-attached IPM Controller specification, standardizes methods for attaching management controllers to in-shelf LANs (usually Ethernet).
HPM.3, the DHCP-assigned platform management parameters specification, defines how a DHCP server can be configured to assign HPM parameters, especially IP addresses, for use by the HPM layer, all on an implementation-independent basis. Both HPM.2 and HPM.3 were adopted in 2012.
In the context of the image above, HPM.1 is represented by the upgrade agent in the lower left corner; according to HPM.1, it can communicate via a Shelf Manager with any of the listed management controller types to deliver relevant upgrade images for installation on those controllers. HPM.2 adds standardized ways to those controllers to connect directly with an in-shelf LAN (shown in the figure with dashed red line); these connections allow an HPM.1 upgrade agent to communicate directly with any LAN-attached controllers, bypassing its owning Shelf Manager. The direct connections facilitate additional applications, including serial over LAN, IPMI message tracing, and general communication with system managers and network clients, all as shown in the figure. HPM.3 provides a standardized DHCP-based paradigm for automatic assignment of IP addresses (and other parameters) to enable all this communication.
All the HPM.x specifications use the term “IPM Controller” to refer generically to any type of HPM controller, including the base controllers of ATCA, with that same name, but also AdvancedMC Carrier IPMCs and Module Management Controllers (MMCs) and MicroTCA’s Carrier Managers, MicroTCA Carrier Management Controllers (MCMCs) and Extended MMCs (EMMCs). Shelf Managers include an IPM Controller core and that HPM.x term applies there, as well.
