Distributed Management Task Force, Inc.

DMTF Releases Updated MCTP SMBus/I2C Transport Binding Specification

The DMTF’s Platform Management Components Intercommunication (PMCI) Working Group defines standards to address “inside the box” communication and functional interfaces between the components of the platform management subsystem (e.g., management controllers, managed devices, etc.). PMCI’s Management Component Transport Protocol (MCTP) over SMBus/I2C Transport Binding Specification is now available in version 1.1.0.

This specification addresses how MCTP packets are delivered over a physical SMBus or I2C medium using SMBus transactions. It defines how physical addresses are used, how fixed addresses are accommodated, how physical address assignment is accomplished for hot-plug or other devices that require dynamic physical address assignment, and how MCTP support is discovered.

In addition, timing specifications for bus and MCTP control operations are included, and a "fairness" protocol is defined for the purpose of avoiding deadlock and starvation/lockout situations among MCTP endpoints. The binding has been designed to be able to share the same bus as devices communicating using earlier SMBus/I2C management protocols, such as Alert Standard Format (ASF) and Intelligent Platform Management (IPMI), and with vendor-specific devices using SMBus/I2C protocols. The specification also allows a given device to incorporate non-MCTP SMBus functions alongside MCTP.

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