Incident Library
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Cases8 cases

3 to 7 of 8

  1. IL-0347 About 25% of Scaleway FR-PAR-1 hypervisors lost VPC connectivity when both VPC BGP route reflectors got stuck
    Scaleway2024
    Symptoms

    On 18 October 2024, from 7:50 to 8:01 UTC, about 25% of the hypervisors in Scaleway's FR-PAR-1 availability zone lost VPC connectivity with the rest of the region, and products that use VPC failed with them. Public internet connectivity and Elastic Metal VPC connectivity were not affected.

    Network unreachablePacket lossNode NotReady
    Trigger

    At 6:20 UTC a Top of Rack switch in FR-PAR-1 had a software crash. One of the two BGP route reflectors for VPC ran on a hypervisor in that rack and was left in an abnormal state.

    Root cause
    Software defect
    Component
    Network control plane (SDN)BGP routingNetwork switchDatabaseManaged Kubernetes control plane and provider API
    Contributing factor
    Excessive blast radiusAutomation amplification
    Detection

    Health-check monitoring on both route reflectors detected the anomaly, and the Scaleway Customer Excellence and SRE teams detected the customer impact and opened an incident.

    Remediation
    • Fixed both VPC route reflectors by manual action
    Action items
    • Fixed the autohealing mechanism that had failed to fix route reflectors stuck in a stale state; the fix is https://github.com/FRRouting/frr/pull/17163
    • Run different software versions on the route reflectors so a single bug cannot stop several instances
    • Investigate the software issue that left the route reflectors in a stale state
    View case
  2. IL-0342 DigitalOcean's AMS3, LON1 and SFO2 data centers lost Internet connectivity in repeated waves as edge routers failed
    DigitalOcean2023
    Symptoms

    From 09:55 UTC on 9 August 2023, DigitalOcean's AMS3, LON1 and SFO2 datacenters lost Internet access in waves of 10 to 15 minutes, about an hour apart. Users saw connectivity issues, latency and timeout errors on Droplets and on Droplet-based services such as Load Balancers, Kubernetes and Database clusters.

    Network unreachableIntermittent timeoutsHigh latency
    Trigger

    The edge routers received an RPKI-related routing update, and the operating system software on them crashed its routing process on that update.

    Root cause
    Software defect
    Component
    BGP routing
    Contributing factor
    Excessive blast radiusHarmful manual action
    Remediation
    • Rolled out a software update to the edge routers running the affected version, site by site
    • Rebalanced traffic on the congested routes between AMS3 and FRA1
    • Rolled out the fix to the redundant networking equipment so a failover would not hit the bug
    Action items
    • Upgrade all global edge routers to remove the bug
    • Bring the network upgrades already done in Asia to Europe and North America
    View case
  3. IL-0225 An IGP purge command made every Microsoft WAN router recompute routes, causing global latency, timeouts and packet loss
    Microsoft Azure2023
    Symptoms

    From 07:08 UTC on 25 January 2023, customers saw long network latency and timeouts when connecting to resources in Azure regions and to other Microsoft services such as Microsoft 365 and Power Platform. Microsoft's monitoring detected DNS and WAN issues from 07:11 UTC.

    High latencyIntermittent timeoutsIntermittent connection failuresPacket lossNetwork unreachable
    Trigger

    A network engineer adding capacity to the global WAN in Madrid ran a step of a recently changed standard operating procedure that purged the IGP database; on the router manufacturer involved, that command runs on all IGP-joined routers instead of only the local one.

    Root cause
    Configuration change
    Component
    Backbone network (WAN)Interior routing (IGP)BGP routing
    Contributing factor
    No configuration testsUnverified assumptionExcessive blast radiusHarmful manual action
    Detection

    Monitoring detected DNS and WAN issues from 07:11 UTC and alerted the on-call engineers within 5 minutes of the command being run. The team reviewed all recent changes and identified the command by 08:20 UTC. The engineer making the change was not informed of the alerts because of the unqualified changes to the SOP.

    Remediation
    • Restarted by hand the paused WAN health and traffic engineering systems, which ended the remaining packet loss
    Action items
    • Audit and block similar widespread-impact commands across all three vendors for all WAN router roles
    • Give on-call engineers real-time visibility of approved and unqualified activity on network devices
    • Run regular mandatory operational training and attestation of following all SOPs
    • Have the Change Advisory Board review all SOPs still pending qualification within 30 days
    View case
  4. IL-0539 KT's internet service failed nationwide for about 89 minutes as wrong routes spread from one router in Busan
    KT2021
    Symptoms

    On 25 October 2021 from about 11:16, traffic to the DNS servers in KT's network rose sharply, and then KT's internet service failed across the whole country. KT recognised the internet outage at 11:20, and the outage lasted about 89 minutes until KT finished recovery at about 12:45.

    Network unreachableService outage
    Trigger

    During the replacement of an enterprise network router at KT's Busan office, worked on remotely from the Busan communication center, a worker entered a routing configuration script that lacked the 'exit' command that should have ended the IS-IS part of the configuration.

    Root cause
    Configuration change
    Component
    Interior routing (IGP)BGP routing
    Contributing factor
    Missed in reviewNo configuration testsChange during peak hoursExcessive blast radius
    Detection

    KT recognised the internet outage at 11:20, four minutes after DNS traffic began to surge at 11:16. The Ministry of Science and ICT saw the traffic increase in its own monitoring, and KT reported the outage to the ministry at 11:40.

    Remediation
    • Isolated the router where the faulty routing configuration was entered
    • Logged in to each regional router, deleted the faulty processes and restarted them
    Action items
    • Check the network management of major carriers, including their work procedures and the systems that stop technical errors from spreading
    • Consider having major carriers introduce simulation systems that diagnose errors from network work in advance
    • Have the NMS center and network operations center of each major carrier check technically that approved work plans are followed
    • Strengthen safeguards in routing work, such as limiting the number of route entries updated at once below a set level
    • Strengthen the monitoring of carriers' outages and develop technology, including AI-based preventive diagnosis, for network stability and resilience
    • Prepare structural measures for a stable network architecture and network survivability
    • Let carriers notify users of outages through SNS, text messages and other means, not only the website
    Lessons

    The investigation named management problems and technical problems. On the management side, work approved for the night was done during the day, partner company workers did the routing work without a work manager, and the work was done with the network still connected. On the technical side, the two pre-verification steps were people reading the script and missed the missing 'exit', there was no virtual testbed for trying the work on a disconnected network, and nothing stopped an error in one region from spreading to the whole country.

    View case
  5. IL-0228 IPv4 routing across OVHcloud's global network broke after a router change put the full internet routing table into OSPF
    OVHcloud2021
    Symptoms

    At 09:20 CET on 13 October 2021, during a planned change on a router, IPv4 traffic across OVHcloud's whole network stopped being routed, while all IPv6 traffic stayed reachable. The team detected a problem with the router's performance at 09:21 CET and escalated at once.

    Network unreachableService outage
    Trigger

    A planned change to a router in the Vint Hill datacentre in the United States, meant to strengthen anti-DDoS protection, included a command to regulate the redistribution of BGP into OSPF, and the router did not interpret that command correctly.

    Root cause
    Configuration change
    Component
    Interior routing (IGP)BGP routingBackbone network (WAN)
    Contributing factor
    Ineffective rollbackExcessive blast radius
    Detection

    At 09:21 CET the team detected a problem with the router's performance and started the escalation process.

    Remediation
    • Disconnected the optical equipment to isolate the router's connectivity
    • Powered off the faulty router
    • Stabilised connectivity to restore the remaining services
    Action items
    • Re-evaluate the change procedure for this type of equipment, which applies the command line natively
    • Strengthen the related change process
    View case
Check your cluster for this

These 8 cases involve BGP routing 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.

Open kubegap

By root cause3

Capacity exhaustion2 cases

Component
BGP routing2CDN and edge network1Database1InfiniBand fabric1Transit gateway or network interconnect1Model hub1Network control plane (SDN)1NIC, cable and switch port link1
Contributing factor
Excessive blast radius2Automation amplification1Harmful manual action1No headroom1
Organisation
Cloudflare1IONOS Cloud1
  1. IL-0350 Hosts in an IONOS TXL cluster lost connectivity when an InfiniBand fabric resweep failed on a full multicast table
    IONOS Cloud2026
  2. IL-0341 Traffic between Cloudflare and AWS us-east-1 had high latency, packet loss and origin failures for almost four hours
    Cloudflare2025

Software defect3 cases

Component
BGP routing3Network control plane (SDN)2Backbone network (WAN)1Database1Managed Kubernetes control plane and provider API1Network switch1
Contributing factor
Excessive blast radius3Automation amplification1Circular dependency1Limited debug access1Harmful manual action1Ineffective rollback1
Organisation
DigitalOcean1Google Cloud1Scaleway1
  1. IL-0347 About 25% of Scaleway FR-PAR-1 hypervisors lost VPC connectivity when both VPC BGP route reflectors got stuck
    Scaleway2024
  2. IL-0342 DigitalOcean's AMS3, LON1 and SFO2 data centers lost Internet connectivity in repeated waves as edge routers failed
    DigitalOcean2023
  3. IL-0222 Google Cloud US regions had heavy packet loss and some went unreachable after the network control plane was descheduled
    Google Cloud2019

Configuration change3 cases

Component
BGP routing3Interior routing (IGP)3Backbone network (WAN)2
Contributing factor
Excessive blast radius3No configuration tests2Unverified assumption1Change during peak hours1Harmful manual action1Ineffective rollback1Missed in review1
Organisation
KT1Microsoft Azure1OVHcloud1
  1. IL-0225 An IGP purge command made every Microsoft WAN router recompute routes, causing global latency, timeouts and packet loss
    Microsoft Azure2023
  2. IL-0539 KT's internet service failed nationwide for about 89 minutes as wrong routes spread from one router in Busan
    KT2021
  3. IL-0228 IPv4 routing across OVHcloud's global network broke after a router change put the full internet routing table into OSPF
    OVHcloud2021