Incident Library
Applied filters ComponentNetwork control plane (SDN)SymptomHigh latencyFactorExcessive blast radiusClear allEvery case under the filters, with no sentence; newest first.
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Cases2 cases

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  1. IL-0339 Azure Front Door and Azure CDN users saw intermittent connection errors, timeouts and latency spikes for hours
    Microsoft Azure2024
    Symptoms

    From 11:45 UTC on 30 July 2024, a subset of customers got intermittent connection errors, timeouts and latency spikes when connecting to Microsoft services that use Azure Front Door (AFD) and Azure Content Delivery Network (CDN). The Azure Portal team saw the first service degradation at 11:47 UTC.

    Intermittent connection failuresIntermittent timeoutsHigh latencyPacket loss
    Trigger

    Around 11:45 UTC the Azure network DDoS protection service was disengaging after a routine DDoS mitigation and returning traffic to its default routing to AFD, but the routes at one site in Europe could not be updated because the network control plane could not reach that site during a local power outage.

    Root cause
    Configuration change
    Component
    CDN and edge networkDDoS protection serviceNetwork control plane (SDN)Data center power and cooling
    Contributing factor
    Overlapping failuresExcessive blast radiusMonitoring blind spot
    Detection

    The Azure Portal team detected service degradation at 11:47 UTC and began to investigate. At 12:10 UTC network monitoring correlated the Portal incident to a network issue at one site in Europe, and networking engineers joined.

    Remediation
    • Rerouted traffic under the standard congestion playbook, which removed most of the impact by 13:58 UTC
    • Ordered the network control plane to reissue its commands to the misbehaving device, which could not be reached
    • Removed the device that kept attracting traffic from the network and scanned the network for other issues
    Action items
    • Add the missing configuration on network devices so a DDoS mitigation issue in one geography cannot spread to another
    • Improve validation and monitoring in the Azure network to detect invalid configurations
    • Improve monitoring for when the DDoS protection service is unreachable from the control plane but still serving traffic
    View case
  2. IL-0222 Google Cloud US regions had heavy packet loss and some went unreachable after the network control plane was descheduled
    Google Cloud2019
    Symptoms

    On Sunday 2 June 2019, with user impact beginning between 11:47 and 11:49 US/Pacific, Google Cloud projects in several US regions saw elevated packet loss from network congestion, and some regions became unreachable. Customers saw higher latency, intermittent errors and lost connectivity to instances in us-central1, us-east1, us-east4, us-west2, northamerica-northeast1 and southamerica-east1, while us-west1, Europe and Asia had no regional congestion.

    Packet lossNetwork unreachableHigh latencyHigh error rateMonitoring outage
    Trigger

    At 11:45 US/Pacific a relatively rare type of datacenter maintenance event started in one physical location, and the automation that runs it descheduled logical clusters that also held network control plane jobs in other physical locations.

    Root cause
    Software defect
    Component
    Network control plane (SDN)BGP routingBackbone network (WAN)
    Contributing factor
    Excessive blast radiusCircular dependencyLimited debug accessIneffective rollback
    Detection

    Google engineers were alerted to the failure two minutes after it began and started the incident process used for the most serious production incidents. The first customer notice appeared on the status page at 12:53 US/Pacific.

    Remediation
    • Lowered the priority of less critical network traffic classes to reduce congestion
    • Halted the datacenter automation software responsible for the maintenance event
    • Rescheduled the network control plane and its supporting infrastructure in each location
    • Rebuilt and redistributed the lost network control plane configuration, rolling it out from 14:03
    • Directed service traffic away from the affected regions
    • Moved the Cloud VPN control plane in three regions out of its fail-safe state
    Action items
    • Keep the maintenance automation off until safeguards stop it descheduling jobs in several physical locations at once
    • Harden the cluster management software to reject such requests whatever their origin
    • Reconfigure the network control plane to reject maintenance requests of the type involved
    • Make the network control plane in each location persist its configuration
    • Let the network stay in fail static mode longer when the control plane is lost
    • Review, update and test emergency response tooling and procedures, including customer communication tooling, for such network failures
    • Extend continuous disaster recovery testing to this and similarly catastrophic failures
    View case
Check your cluster for this

These 2 cases involve Network control plane (SDN) and Backbone network (WAN). kubegap audits a Kubernetes cluster for gaps like these, read-only, from Claude Code or Codex; its checks cite public reports like the ones in this library.

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By root cause2

Configuration change1 case

Component
CDN and edge networkData center power and coolingDDoS protection serviceNetwork control plane (SDN)
Contributing factor
Excessive blast radiusMonitoring blind spotOverlapping failures
Organisation
Microsoft Azure
  1. IL-0339 Azure Front Door and Azure CDN users saw intermittent connection errors, timeouts and latency spikes for hours
    Microsoft Azure2024

Software defect1 case

Component
Backbone network (WAN)BGP routingNetwork control plane (SDN)
Contributing factor
Excessive blast radiusCircular dependencyLimited debug accessIneffective rollback
Organisation
Google Cloud
  1. IL-0222 Google Cloud US regions had heavy packet loss and some went unreachable after the network control plane was descheduled
    Google Cloud2019