Data Tunnel Protocol (DTP) Specification
Version: Draft Target Version: 2025-10-25 Status: Draft, awaiting review Protocol Layer: Application Layer
Introduction
This specification defines the wire format, state machine, negotiation mechanism, encryption requirements, error handling, and version management rules of the Data Tunnel Protocol (DTP). DTP is the application-layer protocol used in the iFay ecosystem for bidirectional data collection and injection between terminal devices and Fay.
This specification is the normative document of DTP. Any implementation conforming to this specification ought to be capable of interoperating with other conforming implementations.
Keywords Convention
The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD, SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL in this document are to be interpreted as described in RFC 2119 and RFC 8174, and only have normative meaning when they appear in bold form.
Document Structure
This specification consists of 10 chapters:
| Chapter | Title | Scope |
|---|---|---|
| Chapter 1 | Overview and Positioning | DTP's role, design goals, relationship with other protocols, and version management & compatibility (§1.7, normative) |
| Chapter 2 | Terminology and Definitions | Normative terminology definitions |
| Chapter 3 | Protocol Architecture | Protocol layering, components, and state machine |
| Chapter 4 | Logical Frame Structure | Binary format of frame header and payload |
| Chapter 5 | Negotiation Mechanism | Agreement negotiation, adjustment, and termination |
| Chapter 6 | Data Transmission | Data collection and injection workflows |
| Chapter 7 | Security and Encryption | End-to-end encryption requirements |
| Chapter 8 | Reliability | Resume, acknowledgment, and session management |
| Chapter 9 | Error Handling | Error codes and notification mechanism |
| Chapter 10 | Version Management | Operational mechanisms and governance flow of version management (authoritative policy in Chapter 1 §1.7) |
Conformance
Any entity claiming to implement DTP (hereinafter referred to as "implementation") MUST satisfy the following conformance requirements:
- The implementation MUST fully support all MUST rules defined in this specification.
- The implementation SHOULD support all SHOULD rules defined in this specification. If unsupported, the implementation MUST explicitly disclose the deviation in its documentation.
- The implementation MAY choose whether to support MAY rules.
- The implementation MUST NOT introduce extensions that conflict with this specification. Any extension MUST be implemented through the extension mechanisms defined in this specification (see Chapter 4 custom fields, Chapter 5 agreement parameter extensions).
Normative References
- RFC 2119 — Key words for use in RFCs to Indicate Requirement Levels
- RFC 8174 — Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words
- RFC 4122 — A Universally Unique IDentifier (UUID) URN Namespace (used for Fragment_ID, Agreement_ID, Session_ID)
- RFC 3339 — Date and Time on the Internet: Timestamps (UTC timestamp format)
- CAP Specification — Control Authorization Protocol; DTP relies on CAP for identity authentication and key exchange
Related Documents
- DTP Blueprint (
docs/en/blueprint/): Non-normative introductory material for DTP, providing motivation, design rationale, and examples - DTP Schema (
schema/draft/schema.ts): Reference TypeScript type definitions for DTP