Overview
ISO/IEC 21558-1:2022 defines the switching and routing architecture of the Future Network (FN). It specifies how FN handles packet delivery, separates forwarding metadata from packet payloads, and supports both real‑time audiovisual (AV) and traditional information‑technology (IT) traffic. The standard is part of the FN series and works with protocol definitions in ISO/IEC 21559‑1 and requirements in ISO/IEC TR 29181.
Key topics and requirements
- Two main services: an ultra‑low‑latency AV service for regular-interval media traffic (audio/video) and a best‑effort IT service for general data.
- Flows: FN defines three flow types - AV flows (single source, multicast destinations), connection‑oriented IT flows (single source/destination), and connectionless IT flows (multiple sources, single destination).
- Encapsulation and payload rules: each packet contains an encapsulation (forwarding information) and an opaque payload (octet string) that intermediate elements do not process.
- Forwarding model: routing/forwarding information is carried separately from packet headers, reducing encapsulation size and simplifying switch forwarding; flow identifiers appear in signalling, not in packet headers.
- Service levels: three levels - best‑effort, asynchronous (bounded latency with resource reservation), and synchronous (well‑defined latency with tight synchronisation and timeslots).
- Links and topology:
- Physical links implement tight synchronisation and can support synchronous service.
- Virtual links are carried over non‑FN technologies and do not meet tight synchronisation requirements.
- Network composition uses islands (elements connected by physical links) and clouds (islands connected by virtual links).
- Lower‑layer requirements: physical point‑to‑point links must provide a stream of octets with formatting that allows octet positioning; virtual link behaviour is defined in ISO/IEC 21559‑1.
- QoS and AV considerations: Clauses address packet formats, QoS implications, synchronisation domains, slots/allocations and virtual links for AV traffic.
Practical applications and users
Who uses ISO/IEC 21558‑1:
- Network architects and systems designers planning low‑latency media networks (live audio/video production, broadcast, AV-over-IP).
- Vendors building FN‑compliant switches, routers and signalling systems.
- Service providers and enterprises migrating from IP to Future Network architectures that require deterministic latency and improved mobility handling.
- Standards bodies and implementers referencing FN flow, timing and encapsulation models for interoperability.
Benefits for implementers:
- Enables ultra‑low‑latency AV transport, simpler forwarding logic, smaller encapsulation overhead, and support for mobility without IP‑in‑IP tunnels.
Related standards
- ISO/IEC 21559‑1 - Future network protocols and mechanisms (switching and routing)
- ISO/IEC TR 29181‑1 and TR 29181‑3 - FN problem statement and requirements
- IEC 62379‑5‑2 - Signalling for networked digital audio/video (flow identifiers and setup)