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AMF — Access and Mobility Management Function

The AMF is the control-plane anchor of the 5G core. It terminates the N1 signalling to the UE and the N2 (NGAP) association to each gNodeB, and handles registration and connection management — attaching UEs, keeping them reachable, and paging them when they are idle. It owns the UE contexts (one per registered subscriber, keyed by SUPI) and the gNB associations (one per connected radio, keyed by SCTP association), and it selects the SMF for each PDU session while relaying session requests between the UE and the SMF. When a subscriber is on the network, the AMF is the NF that knows where they are and how to reach them.

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In the dashboard​

The AMF dashboard — health cards, API/NRF/NF status detail, and statistics (registered/connected UEs, connected gNodeBs)

The AMF dashboard opens with the four standard health cards — API Health, NRF Registration (whether the AMF is currently registered with the NRF), NF Status, and License — each polling on an interval. Below them, it surfaces the data the AMF owns:

  • UE List — every UE context the AMF holds, keyed by SUPI, with its registration and connection state. This is the "who is attached right now" view. Selecting a UE opens its detailed context, and the AMF can also list a UE's active PDU sessions by SUPI.
  • gNodeBs — the connected radios, one row per SCTP association. The table decodes the raw NGAP values into readable gNB-ID, TAC (tracking area), PLMN, and SST (slice/service type), so an operator can confirm which cells are up and which tracking areas and slices they serve without decoding identifiers by hand. Selecting a row opens the detailed gNB by its SCTP association ID.
  • Statistics — the AMF's live counters (registered UEs, connected gNBs, and signalling volumes), for a quick read on load and activity.
  • Maintenance Mode — whether the AMF is in maintenance, used to drain or hold a node during planned work.
  • Configuration — the runtime configuration the service is currently using.

Actions​

The dashboard exposes actions to recover from stuck state. Each is confirmed before it runs, since they clear live state:

  • Clear All UE Contexts (bulk) — removes every UE context from the AMF. Use as a last resort to recover a node holding stale or corrupt contexts; every affected UE must re-register.
  • Clear Cache (bulk) — clears the AMF's NF-discovery cache and UE caches. Use when the AMF is acting on stale peer or lookup data — for example, after an NF has moved or re-registered.
  • Deregister (per-UE) — deregisters a single UE and cleans up its state. Use to drop one subscriber's context that will not clear on its own, rather than resetting the whole node.

Beyond the dashboard buttons, the AMF's OAM API exposes finer-grained recovery controls an operator can reach through the backend proxy:

  • Force-disconnect a gNB — tears down a single gNB by its SCTP association ID. Use to clear a wedged or misbehaving radio association without touching the others.
  • Force-release a PDU session — releases one PDU session by its supi:psi identifier. Use to drop a session that is stuck on the AMF's side while leaving the UE registered.
  • Deregister or page a UE — forces a UE to deregister, or triggers paging to bring an idle UE back to connected. Use paging to test reachability, and forced deregistration to evict a UE cleanly.

Operations​

  • Runtime diagnostics (/api/oam/diagnostics) — shows low-level diagnostics for the running service.
  • Resource usage (/api/oam/resources) — reports the runtime's memory, process, and scheduler usage for a health check on the node.
  • Peers (/api/oam/peers) — lists the configured and discovered NF peer URIs and the current SCTP associations, so an operator can see who the AMF is talking to.
  • NRF discovery cache (/api/oam/nrf_discovery) — shows the contents of the discovery cache — which NF instances the AMF has learned from the NRF.
  • Set log level (/api/oam/log_level) — changes the log level at runtime (one of emergency, alert, critical, error, warning, warn, notice, info, debug) to turn up detail while troubleshooting.
  • Force NRF re-registration (/api/oam/nrf/reregister) — re-registers the AMF with the NRF, used to recover a dropped or stale registration.
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