Telecoms Labs
Operate, troubleshoot and prove the technology — every lab feeds the same Competency Graph as Forge and CBT.
These labs now also run on the universal DexNova Lab Runtime — attempts there feed your competency evidence directly.
Open migrated labsCore Subnet Isolation After VLAN Reconfiguration
Two core server subnets stopped reaching each other right after switch maintenance — trace L2/L3 and restore connectivity.
MME VNF Refuses to Scale During a Signaling Storm
A national event causes an attach storm; the MME VNF cannot scale out and success rates tumble.
Single-Site Outage After Power Maintenance
One site drops off the network after a power maintenance window — read the site controller before touching the core.
Tracking-Area Storm Overloads a Pinned MME
A DNS change collapses the MME pool onto one node — classic EPC pooling failure.
Handover Preparation Failures on a Highway Corridor
Cars lose calls on a highway cluster after a software upgrade — X2 and PCI configuration to the rescue.
Telemetry Poller Crash-Loops on Malformed Payload
The KPI poller for 42 gNBs keeps restarting; one vendor's payload is the culprit.
IMS Registration Failures for a New SIM Batch
Every subscriber on a fresh SIM batch gets a 403 on REGISTER — trace SIP down to the HSS.
Go Metrics Collector Panics on Short gRPC Payload
The Go KPI collector crash-loops on a malformed payload from one agent.
URLLC Robots Land on the Wrong Network Slice
A factory's URLLC robots breach their latency SLA — because their traffic isn't on the URLLC slice at all.
New gNB Fails NG Setup with a Node-ID Conflict
A new site cannot register to the 5G core — the SCTP handshake succeeds, so look at NGAP.
SCTP Association Flapping on the OAM Ring
An association resets every 30 seconds — the answer sits in the switch's MAC table.
UPF Rejects PFCP Session Establishment for Roamers
Roamers have no data: the SMF is handing the UPF an F-SEID it cannot route to.
Firewall Auto-Remediation Blackholes All SCTP During a Flood
A DDoS playbook blocks SCTP network-wide — every gNB in the region drops off the core.
Diameter Peer Overload at HSS During Peak Hour
Watchdog timeouts at 7pm — the load balancer's health checks are the flood.
GTP-U Error Indication Storm After SGW Failover
Throughput collapses right after an SGW failover — stale TEIDs are unrouting every packet.
5G-AKA Rejects for a New SIM Batch
A new SIM batch fails every authentication — the vectors never reached the UDM.
Blocked Egress Port
The new payment integration can't connect — one port times out while another works. Read the firewall policy.
Backup Permission Denied
A backup job that ran for months suddenly fails with permission errors. Find what changed.
DNS Resolution Failure
Users cannot reach the company portal while general internet browsing still works — diagnose from resolver logs and firewall events.
Container Network Isolation
Both containers run on the same host, yet the app can't reach the database. Container networking basics.
Silent Order Pipeline
Orders flow into the platform but nothing is processed after a release. A classic producer/consumer mismatch.
5G Registration Failure — NG Signalling Down
5G UEs camp on the network but registration never completes. Trace the NGAP signalling path.
PDU Session Establishment Failure
UEs register fine and show 5G signal, but every PDU session fails. Read the SMF's rejection cause.
Asymmetric Route Blackhole
The branch can reach the internet, but replies from the HQ finance server never come back. Spot the asymmetric routing.
CrashLoopBackOff
A new Kubernetes deployment never becomes ready. Read the pod events and find the missing configuration.
SSH Service Won't Start
After a maintenance window the jump host refuses SSH. The service log tells the whole story.