Packets, Messages, and Flits

CHI doesn't use simple signals. Data is encapsulated:

• Message: A protocol-level action (e.g., "I want to read address X").
• Packet: The Link-layer representation of a message, containing routing info (ID, Destination ID).
• Flit (Flow Control Unit): The smallest unit of transfer across a physical link. A packet can be 1 or more flits.

CHI uses Virtual Networks (VNs) to avoid deadlocks:

• REQ: Request channel.
• RSP: Response channel.
• DAT: Data channel.
• SNP: Snoop channel.