Core Protocols
The three protocols form a stack where MCTP is the foundation:
graph TD
PLDM["PLDM<br/>(FW Update · Monitoring)"] --> MCTP
SPDM["SPDM<br/>(Attestation · Security)"] --> MCTP
MCTP["MCTP<br/>(Message Transport Layer)"] --> SMBus["SMBus/I2C"]
MCTP --> PCIe["PCIe-VDM"]
MCTP --> USB["USB"]
style PLDM fill:#4a70a0,color:#fff
style SPDM fill:#509060,color:#fff
style MCTP fill:#a09825,color:#fff
style SMBus fill:#a05050,color:#fff
style PCIe fill:#a05050,color:#fff
style USB fill:#a05050,color:#fff
Protocol Deep Dives
| Protocol | Role | Details |
|---|---|---|
| MCTP | Transport Layer | Message delivery between components |
| SPDM | Security & Attestation | Identity verification and trust |
| PLDM | Firmware & Monitoring | Management operations |
Key Takeaway
- MCTP = How messages travel (transport)
- SPDM = Who you’re talking to and can you trust them (security)
- PLDM = What you’re actually doing (management operations)