DTN Mesh Routing Engine
Bundle Protocol v7 (RFC 9171) DTN Router with Contact Graph Routing
Delay-Tolerant Networking (DTN) router implementing Bundle Protocol Version 7 (RFC 9171), Contact Graph Routing (CGR), and convergence layers for the lunar surface mesh, with gateway to Earth-link CCSDS frames.
Purpose
Route bundles across intermittently-connected mesh nodes, choosing paths based on predicted contact windows, link quality, and bundle priority — enabling reliable communication even when no end-to-end path exists at the moment of transmission.
Context
Software stack on each mesh node and on the central CDH. Speaks BPv7 with peers, hands off to convergence layers (LTP, TCP, UDP, CCSDS Proximity-1) for actual transport. Per LunaNet Interoperability Specification, BPv7 is the mandated network layer for lunar surface interoperability. Gatewayed to CCSDS Space Packet via L3-COM-EARTH-PROC for Earth-bound traffic.
Principles
- ▸Bundle Protocol stores complete application data units (bundles) at each hop, awaiting next contact — store-and-forward across arbitrary disconnections
- ▸Contact Graph Routing (CGR) uses scheduled or predicted contact plans (from ephemerides and assets schedules) to compute least-delivery-time paths
- ▸Convergence Layer Adapters (CLAs) hide underlying transport: LTP (Licklider Transmission Protocol) for high-loss links, TCP/UDP for terrestrial
- ▸Custody transfer (BPv7) places retransmission responsibility on intermediate nodes — frees source to release resources
- ▸Bundle expiration time (lifetime) ensures stale data doesn't fill storage indefinitely
- ▸Asynchronous Message Service (AMS) over BPv7 enables publish-subscribe pattern over DTN
Typical implementations
- ▸JPL ION (Interplanetary Overlay Network) — reference BPv7 implementation, ported to numerous spacecraft and ground stations
- ▸NASA's HDTN — high-throughput DTN implementation for surface relay
- ▸DTNME (DTN Marshalling Engine) — lightweight C++ BPv7 implementation
- ▸PACE mission (Feb 2024) — first NASA Class-B routine DTN operations, 34M+ bundles, 100% delivery
- ▸ESA Lunar Pathfinder includes DTN gateway
- ▸LunaNet Interoperability Specification v5 (Jan 2025) mandates BPv7 + LTP for lunar relay
Lunar considerations
- ▸Earth-Moon round-trip ~2.6 s is short enough for some interactive protocols, but PSR/topography occultation creates DTN-style outages
- ▸Contact graph must integrate Lunar Pathfinder, LCRNS, and Moonlight orbiter ephemerides for relay routing
- ▸Lunar surface mesh has highly variable link quality (sun-glare interference, dust loading) — CGR must update edge costs dynamically
- ▸100-year mission requires CGR to operate without continuous Earth-supplied contact plan updates — autonomous prediction from on-board ephemeris
- ▸NeuraLunaDTNet (2024) demonstrates neural-network routing for lunar DTN as alternative to CGR for dynamic environments
Specifications
Functional
| primary function | Route Bundle Protocol bundles across the lunar mesh and Earth link with deadline awareness |
| inputs | Bundles from L3-CDH-SW (application layer), Bundles from peer mesh nodes via L3-COM-MESH-NODE, Contact plan from L3-CDH-PROC (predicted from ephemeris), Link quality reports from L3-COM-MESH-NODE |
| outputs | Routed bundles to L3-COM-MESH-NODE for next-hop transmission, Delivered bundles to L3-CDH-SW for application processing, Routing telemetry, custody acknowledgements, bundle expiration events, Bundle queues mirrored to L3-COM-EARTH-BUF for persistence |
| bundle protocol version | BPv7 (RFC 9171) |
| convergence layers | LTP, TCPCL, UDPCL, CCSDS Proximity-1 CLA |
| routing algorithm | Contact Graph Routing (CGR) + Earliest-Arrival |
| max concurrent bundles | 10000 |
| max bundle size mb | 100 |
| custody transfer enabled | True |
| throughput mbps min | 5 |
Physical
| mass kg | 0.0 |
| dimensions | Software on L3-CDH-PROC and L3-COM-MESH-NODE controllers |
| materials | Code in rad-hardened NOR flash |
| operating temperature c | -40, 70 |
Operational
| power consumption w | 2 |
| thermal range c | -40, 70 |
| lifetime years | 100 |
| mtbf hours | 500000 |
| software loc | 60000 |
| verification standard | NASA-STD-8739.8 Class B |
Interfaces
Provides
- Routed bundle stream with destination addressing
- Delivered application bundles
- Bundles destined for Earth (gateway to CCSDS)
Requires
- Received bundles and link metrics
- Persistent bundle storage
- Contact plan (ephemerides) and CPU cycles
Cite this entry
Lunar Ark Codex. "DTN Mesh Routing Engine" (L3-COM-MESH-ROUT). Retrieved 10 September 2026, from https://lunarark.com/entry/L3-COM-MESH-ROUT
Licensed CC-BY-SA 4.0. You may reuse and adapt this entry with attribution, under the same licence.