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Designing a 6G core that survives signalling storms

CT4’s resilience study (TR 29.842) organises its work around three phases: preventing failures, handling them while they happen, and recovering afterwards. It already has eight solutions, from load control within NF Sets to dual user-plane paths.

In 60 seconds

  • Three key issues with 13 sub-issues: prevention, handling during perturbation, and recovery.
  • Eight solutions, including a Set Front End for load balancing, NF “sub-health” states, bulk context transfer, and dual UP paths.
  • Why: CT4’s chair cites signalling storms as the cause of 69% of the outage incidents studied.
  • Rapporteur: Nivedya Parambath Sasi, Samsung R&D Institute India.
CTCT4 · TR 29.842 v0.3.0

The key issues

PhaseSub-issues
KI#1 PreventionCN entity load control · end-to-end load control against cascades · AI monitoring of minor impairments
KI#2 During perturbationrapid fault location and isolation · procedure optimisation · seamless migration · disaster overload control · AI/ML-assisted handling · minimum service for priority subscribers
KI#3 RecoveryNF and service recovery · emergency continuity · recovery in network sharing · massive signalling after recovery
CTCT4

The eight solutions

  • 1 – Set Front End (SFE): instance selection and load balancing inside an NF Set without triggering storms of association updates.
  • 2 – Dynamic adaptive configuration: NAS timers and access-control parameters adjusted in real time to load and user type.
  • 3 – Sub-health state: a standard definition of degraded-but-up NF states, with a new SubHealthInfo IE for early warning.
  • 4 – Seamless migration: real-time context sync so a backup NF takes over within milliseconds.
  • 5 – Intelligent monitoring: AI detection of minor impairments before they cascade.
  • 6 – Bulk context transfer: mass migration of subscription and session data during major failures.
  • 7 – Dual UP paths: redundant user-plane paths.
  • 8 – Explicit LCI/OCI request: negotiated load and overload control information.
CT3GPP Highlights · CT4 chair

The case for it

In 3GPP Highlights, Rong Wang and CT4 chair Yue Song (China Mobile) break down real outages: about 50% system unavailability, 38% operational errors, 6% disasters and 6% attacks. They add that signalling storms triggering overload caused 69% of such incidents. Their 6G requirements:

  • Minimize service outage at the architectural level
  • Proactive anomaly prevention and interception
  • End to end failure localization, failure control and failure recovery
  • Network domain isolation and edge reliability

Still open

Conclusions are FFS. The solutions are proposals, not agreements.

Watch next

  • CT4 Calgary (16–20 Nov): first evaluation of the eight solutions.
  • SA2: whether NF Sets and SCP-based routing carry into the 6G architecture. Solution 1 assumes they do.

Sources

Report contents are read from FriendlySpec renders of the draft TRs. Drafts change at every meeting; nothing in a draft TR is agreed until its conclusions are. Outage percentages are the article authors’ figures.