Protocol Overview¶
XGL v2 replaces the old small packed-header model with a fixed base header, TLV extensions, and an authentication trailer. The goal is a clear, verifiable, routable protocol that still fits MCU constraints.
flowchart LR
App[Application API] --> Transport[Transport]
Transport --> Network[Network / Routing]
Network --> Datalink[Data Link]
Datalink --> Wire[Wire Parser / Frame]
Wire --> Phy[PHY]Layer Responsibilities¶
| Layer | Responsibility |
|---|---|
| API | Lifecycle, send APIs, stats, runtime deadlines |
| Transport | Reliable queue, ACK/SACK, RTT, fragments |
| Network | 16-bit nodes, route lookup, TTL, forwarding |
| Data Link / Wire | Header coding, parser, CRC, authentication trailer |
| Platform | Allocator, time, mutex, atomics, PHY callbacks |
Production Rules¶
- Every wire field is explicitly little-endian encoded.
- CRC failures, authentication failures, and length violations fail closed.
- Mutable routing fields and security boundaries must stay explicit.
- Embedded profiles must document memory, deadlines, and ISR boundaries.
How to Read the Full Protocol¶
- Start with Architecture to understand module boundaries and TX/RX flow.
- Then read Implementation Map to connect protocol rules to source files and tests.
- Read State Machines to understand parser, datalink, network, transport, and fragment runtime states.
- Continue with wire, extensions, reliability, security, routing, and fragmentation pages by topic.
- Before release, review the Validation Matrix and Production Checklist.