ltp#

Pure OCaml implementation of Licklider Transmission Protocol (RFC 5326) for reliable data delivery over high-delay and disruption-prone links.

Overview#

LTP is designed for deep-space communications where round-trip times can be minutes to hours. It provides selective acknowledgment and retransmission with support for both reliable and unreliable data segments.

Features#

• SDNV (Self-Delimiting Numeric Value) encoding/decoding
• Session management with engine/session IDs
• Data segment types:
  • Red segments - reliable with acknowledgment
  • Green segments - best-effort delivery
• Control segments:
  • Report segments (acknowledge received ranges)
  • Report-ack segments
  • Cancel segments
• Checkpoint and report-based flow control

Installation#

opam install ltp

Usage#

open Ltp

(* Create a session ID *)
let session = { originator = 1L; number = 42L }

(* Encode an SDNV value *)
let encoded = encode_sdnv 127L

(* Decode an SDNV value *)
match decode_sdnv encoded 0 with
| Ok (value, _offset) -> Printf.printf "Value: %Ld\n" value
| Error msg -> Printf.printf "Error: %s\n" msg

Related Work#

• ION - NASA/JPL DTN with LTP
• µD3TN - Lightweight DTN with LTP support

References#

• RFC 5326 - LTP Specification
• RFC 5325 - LTP Motivation
• RFC 5327 - LTP Security Extensions

Licence#

ISC License. See LICENSE.md for details.