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The Architectural Refinement of μD3TN: Toward a Software-Defined DTN Protocol Stack

Felix Walter, Marius Feldmann, Juan A. Fraire, Scott Burleigh

TL;DR

The paper addresses the需要 for robust, flexible DTN protocol stacks suitable for space networks. It presents µD3TN as a modular software-defined successor to µPCN, with platform independence, BPv6/BPv7 support, abstract CLAs, and an application-facing AAP 2.0. Key contributions include the Generic Bundle Forwarding Interface, Bundle-in-Bundle Encapsulation, persistent storage via CLA, and AAPv2, plus a design that enables runtime reconfigurability and cross-language prototyping in Rust. The work demonstrates through OPS-SAT field tests and REDMARS2 experiments that the architecture supports scalable, interoperable DTN deployments and offers a path toward SDN-like control of the DTN data plane.

Abstract

This paper provides a comprehensive overview of the uD3TN project's development, detailing its transformation into a flexible and modular software implementation of the Delay-/Disruption-Tolerant Networking (DTN) Bundle Protocol. Originating from uPCN, designed for microcontrollers, uD3TN has undergone significant architectural refinement to increase flexibility, compatibility, and performance across various DTN applications. Key developments include achieving platform independence, supporting multiple Bundle Protocol versions concurrently, introducing abstract Convergence Layer Adapter (CLA) interfaces, and developing the so called Application Agent Protocol (AAP) for interaction with the application layer. Additional enhancements, informed by field tests, include Bundle-in-Bundle Encapsulation and exploring a port to the Rust programming language, indicating the project's ongoing adaptation to practical needs. The paper also introduces the Generic Bundle Forwarding Interface and AAPv2, showcasing the latest innovations in the project. Moreover, it provides a comparison of uD3TN's architecture with the Interplanetary Overlay Network (ION) protocol stack, highlighting some general architectural principles at the foundation of DTN protocol implementations.

The Architectural Refinement of μD3TN: Toward a Software-Defined DTN Protocol Stack

TL;DR

The paper addresses the需要 for robust, flexible DTN protocol stacks suitable for space networks. It presents µD3TN as a modular software-defined successor to µPCN, with platform independence, BPv6/BPv7 support, abstract CLAs, and an application-facing AAP 2.0. Key contributions include the Generic Bundle Forwarding Interface, Bundle-in-Bundle Encapsulation, persistent storage via CLA, and AAPv2, plus a design that enables runtime reconfigurability and cross-language prototyping in Rust. The work demonstrates through OPS-SAT field tests and REDMARS2 experiments that the architecture supports scalable, interoperable DTN deployments and offers a path toward SDN-like control of the DTN data plane.

Abstract

This paper provides a comprehensive overview of the uD3TN project's development, detailing its transformation into a flexible and modular software implementation of the Delay-/Disruption-Tolerant Networking (DTN) Bundle Protocol. Originating from uPCN, designed for microcontrollers, uD3TN has undergone significant architectural refinement to increase flexibility, compatibility, and performance across various DTN applications. Key developments include achieving platform independence, supporting multiple Bundle Protocol versions concurrently, introducing abstract Convergence Layer Adapter (CLA) interfaces, and developing the so called Application Agent Protocol (AAP) for interaction with the application layer. Additional enhancements, informed by field tests, include Bundle-in-Bundle Encapsulation and exploring a port to the Rust programming language, indicating the project's ongoing adaptation to practical needs. The paper also introduces the Generic Bundle Forwarding Interface and AAPv2, showcasing the latest innovations in the project. Moreover, it provides a comparison of uD3TN's architecture with the Interplanetary Overlay Network (ION) protocol stack, highlighting some general architectural principles at the foundation of DTN protocol implementations.
Paper Structure (18 sections, 7 figures)

This paper contains 18 sections, 7 figures.

Table of Contents

  1. Introduction
  2. Background
  3. DTN/BP Stacks Overview
  4. From µPCN to µD3TN
  5. Design Decisions and the Evolution of µD3TN
  6. Concurrency and message-passing (2015)
  7. Achieving platform independence (2016)
  8. Concurrent support for BPv6 and BPv7 (2017)
  9. An abstract CLA interface (2018)
  10. AAP: a flexible application interface (2019)
  11. Enhancements based on OPS-SAT testing (2020-2021)
  12. Bundle-in-Bundle Encapsulation (2021)
  13. Concept: Generic Bundle Forwarding Interface (2022-23)
  14. Persistent storage accessible via a CLA (2024)
  15. AAPv2 and forwarding modules (2024)
  16. ...and 3 more sections

Figures (7)

  • Figure 1: The components of µPCN v0.1.0 as depicted in impl:upcn.
  • Figure 2: The updated CLA subsystem is separated into a generic part and a CLA-specific part. Both are connected via an abstract interface, which has to be implemented by each particular CLA.
  • Figure 3: The components of µD3TN v0.13.0 and their interaction, after the removal of the Router Task.
  • Figure 4: The Generic Bundle Forwarding Interface concept uses a Bundle Dispatcher Module (BDM) for forwarding decisions, as depicted in gbfi.
  • Figure 5: The AAP 2.0 state machine, showing that either the AAP 2.0 client or µD3TN issues commands (remote procedure calls) to the other process, which always have to be answered. The direction of control is set once by the ConnectionConfig message and stays that way for the duration of the connection.
  • ...and 2 more figures