ISO 20105:2015

Overview

ISO 20105:2015 - "Space data and information transfer systems - Operation of CFDP over encapsulation service" is an ISO adoption of a CCSDS Recommended Practice that specifies how the CCSDS File Delivery Protocol (CFDP) should operate over the CCSDS Encapsulation Service. The document defines the communications architecture, the minimum service CFDP expects from underlying layers, and how those expectations are reconciled with the capabilities offered by the Encapsulation Service for Earth‑to‑spacecraft, spacecraft‑to‑Earth, and spacecraft‑to‑spacecraft communications.

Key Topics

• CFDP behavior and QoS: CFDP supports modes from best‑effort to fully reliable file transfer and is optimized for long‑delay, noisy, and disjoint links common in space missions.
• Encapsulation Service interaction: Describes the service model provided by the CCSDS Encapsulation Service and how CFDP can be mapped onto it.
• Communications architecture: Defines layer interactions, protocol data units, and the packet communication service assumptions CFDP requires.
• Service reconciliation: Explains equivalencies and adjustments needed where CFDP’s required underlying services differ from what encapsulation provides.
• Applicability and constraints: Applies to any mission or equipment claiming CCSDS‑compliant CFDP operation over a single CCSDS space link.
• Informative guidance: Annexes cover operation over long‑haul/planetary links (Annex B), options for deployment into ground‑station networks (Annex C), and definitions/abbreviations.

Applications

• Implementing reliable or best‑effort file transfer for spacecraft telemetry, science data delivery, software updates, and payload data distribution.
• Designing flight and ground systems for cross‑agency and multi‑partner missions that must interoperate using standard CCSDS services.
• Planning communications for long‑delay or noisy links (e.g., deep‑space, planetary) and proximity or inter‑spacecraft exchanges.
• Integrating CFDP into ground station networks and ensuring consistent behavior when operating over CCSDS Encapsulation Service links.

Who Should Use This Standard

• Space mission systems engineers and architects
• Spacecraft and ground‑segment software developers (protocol implementers)
• Ground station and network integrators/operators
• Space agencies and contractors planning cross‑support and interoperable missions

Related Standards

• CCSDS File Delivery Protocol (CFDP) - CCSDS 727.0‑B‑4
• CCSDS Encapsulation Service - CCSDS 133.1‑B‑2
• Proximity‑1 Space Link Protocol (data link layer) - CCSDS 211.0‑B‑5
• Other CCSDS space link and data‑link recommendations referenced in ISO 20105:2015

ISO 20105:2015 is a Recommended Practice (CCSDS guidance adopted as an ISO standard) intended to help teams implement consistent, interoperable CFDP-over-encapsulation solutions across diverse space mission scenarios.