Overview
ISO/IEC 5021-2:2023 - "Telecommunications and information exchange between systems - Wireless LAN access control - Part 2: Dispatching platform" specifies the functions, interfaces and operating mechanisms of the Cloud AC Dispatch Platform (CADP) for public WLANs. The standard defines how CADP handles AP association, cloud AC assignment and switchover, backup strategies (N+M), and CADP hot-backup behavior. It applies to public wireless local area network (WLAN) networking scenarios and references CAPWAP (IETF RFC 5415) and related WLAN architecture standards.
Key topics and technical requirements
- CADP functions
- Assigns optimal cloud AC addresses to onboarding APs.
- Provides cloud AC backup addresses and hot backup for resilience.
- Synchronizes AP–AC association data with WLAN NMS.
- Interfaces
- IF1 (CADP ↔ AP): CAPWAP-based control tunnel (UDP port 5246). The standard defines CAPWAP preamble and header values (e.g., Version = 0, Type = 0, HLEN = 2, WBID = 1) and limits interface payload to control messages for AP discovery/response.
- IF2 (CADP ↔ WLAN NMS): HTTP/HTTPS interface for the WLAN NMS to provision AP–AC associations, APConfig and fault notifications.
- AP association workflow
- APs are pre-configured with a CADP domain name, obtain CADP IP via DNS/DHCP, send CAPWAP Discovery Request with WTP Board Data, receive Discovery Response containing the assigned cloud AC IP, then re-initiate CAPWAP join to that AC.
- Switchover & backup
- CADP supports cloud AC switchover initiated by WLAN NMS, N active / M backup AC relationships (N+M), and rollback when the failed AC recovers.
- High availability
- CADP hot backup: active and standby CADPs synchronize with WLAN NMS; a recommended synchronization interval is 24 hours. APs attempt association to two CADP IPs in sequence for redundancy.
Applications and users
Who uses ISO/IEC 5021-2:2023:
- Network architects and designers implementing public WLANs and cloud-managed Wi‑Fi.
- WLAN equipment vendors (AP, cloud AC, CADP implementations) ensuring interoperability with CAPWAP and WLAN NMS.
- Service providers and operators deploying large-scale public Wi‑Fi who require automated AC assignment, high availability and load-aware AC selection.
- Systems integrators and NMS developers integrating CADP functions and IF2 provisioning.
Practical benefits:
- Streamlines AP onboarding and cloud AC assignment.
- Improves resilience with coordinated AC backup and CADP hot‑standby.
- Enables centralized, load‑aware AC selection to support seamless client roaming.
Related standards
- ISO/IEC 5021-1 (Networking architecture specification)
- ISO/IEC/IEEE 8802-11 (IEEE 802.11 MAC/PHY)
- IETF RFC 5415 (CAPWAP Protocol Specification)
Keywords: ISO/IEC 5021-2:2023, CADP, Wireless LAN access control, WLAN, CAPWAP, cloud AC switchover, AP association, hot backup, WLAN NMS.