Intel® FPGA Programmable Acceleration Card N3000 Board Management Controller User Guide

ID 683709
Date 11/25/2019

2.2. MCTP Packetization Support

MCTP Definitions

  • The message body represents the payload of an MCTP message. The message body can span multiple MCTP packets.
  • MCTP packet payload refers to the portion of the message body of an MCTP message that is carried in a single MCTP packet.
  • Transmission Unit refers to the size of the portion of the MCTP packet payload.

Transmission Unit Size

  • The baseline transmission unit (minimum transmission unit) size for MCTP is 64 bytes.
  • All MCTP control messages are required to have a packet payload that is no larger than the baseline transmission unit without negotiation. (The negotiation mechanism for larger transmission units between endpoints is message type-specific and is not addressed in MCTP Base specification)
  • Any MCTP message whose message body size is bigger than 64 bytes shall be split into multiple packets for a single message transmission.
MCTP Packet Fields
Figure 2. Generic Packet/Message Fields