Kontron
InterphaseSOLUTIONS ENGINEERING
AMC
MicroTCA.0 Spec Adapts and Extends PICMG Hardware Platform Management
MicroTCA is a new architecture, with definite differences from existing ATCA and AMC platform management approaches. Still, the management architecture preserves compatibility for overall system managers that need to manage MicroTCA shelves along with ATCA shelves, while including significant differences for inside-the-shelf management.
MARK OVERGAARD, PIGEON POINT SYSTEMS
The entire MicroTCA architecture was built around a key ground rule: MicroTCA Must Work With AMC.0-compliant AdvancedMC Modules. This ground rule is essential to preserve the potential for AMC modules to be used in either an ATCA carrier board or a MicroTCA “carrier”—essentially a subrack for AMCs to plug directly into a backplane, plus all the necessary supporting resources, such as power, management, interconnect fabrics and cooling. While there undoubtedly will be AMC modules that are focused for use in one or the other of these environments, the goal of the MicroTCA initiative is to encourage an ecosystem of modules that could be used in either context.
These management issues affect two kinds of AMC/MicroTCA “carriers.” One is an ATCA board that includes connectors for adding AMC cards defined by the AMC.0 specification. The other is a MicroTCA chassis with a backplane that accepts up to 12 ATC modules as defined by the MicroTCA.0 specification. On the management front, this ground rule means that MicroTCA carriers must provide the following for each AMC slot:
• An Intelligent Platform Management Bus-Local (IPMB-L) interface for platform management interactions with the module. The module is required by both specifications to be isolatable so that faults on IPMB-L to one module don’t have to affect the IPMB-L connection to other modules.
• A presence signal to indicate to the carrier (be it an ATCA carrier card with AMC connectors or a MicroTCA backplane chassis) that a module has been inserted in a slot.
• An enable signal to allow the carrier to release the module management controller (MMC) on the module from reset when a module is inserted in a slot and ready to have platform management activated.
Figure 1 shows these key management interfaces of an AMC module. The additional interface shown at the bottom of the module represents as many as 21 high-speed fabric ports that can be implemented on each AMC. As indicated in the figure, AMCs do not connect to the dual redundant IPMB-0 that plays a role in both ATCA and MicroTCA. Each MicroTCA carrier can handle up to 12 AMC modules.
On an ATCA carrier, the carrier IPMC provides local management for the AMC slots it implements and represents any installed AMC modules to the shelf manager over the dual redundant IPMB-0. How are these responsibilities handled in MicroTCA?
MicroTCA Carrier Manager
The carrier manager handles most of these responsibilities in MicroTCA. It interacts over IPMB-L with the AMC modules and represents them to the MicroTCA shelf manager. In addition, however, the carrier manager represents and interacts with the enhanced module management controllers (EMMCs) of MicroTCA-specific module types, including power modules, cooling units and OEM modules. These interactions occur over an intra-carrier IPMB-0 that is functionally equivalent to ATCA’s IPMB-0.
A carrier manager is one of the MicroTCA management components that reside on or interact with a MicroTCA carrier hub (MCH) module. MicroTCA MCHs provide the key management and interconnect facilities of a MicroTCA carrier. For instance, an MCH can include up to 84 lanes of fabric switch facilities, servicing the fabric needs of the installed AMC modules. MCHs can also be implemented on a redundant basis, in which case the fabrics are likely organized as a dual star. Even if dual MCHs are implemented, at any given time there is only a single carrier manager to represent the carrier, and all the resources it hosts, to upper level management.
The final management component that is always implemented on an MCH is the MicroTCA carrier management controller (MCMC), which provides local management for the MCH. An MCMC handles, for instance, E-Keying of the fabrics on its MCH and implements any MCH management sensors, such as the required temperature sensors. The MCMC also uses I2C to access a carrier FRU Info device (typically an I2C SEEPROM) to gather management information about the carrier. This information indicates, for instance, what module slots the carrier implements and, for the AMC and MCH slots, what fabric connections the carrier backplane implements.