Incident Library
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Cases3 cases

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  1. IL-0394 A Cloudflare router in Miami leaked IPv6 BGP routes to peers and providers for 25 minutes, congesting the backbone
    Cloudflare2026
    Symptoms

    On 22 January 2026 from 20:25 UTC, a Cloudflare edge router in Miami sent unintended BGP advertisements of IPv6 prefixes to its transit providers and peers. External networks' traffic was funnelled into the Miami data center, the backbone between Miami and Atlanta became congested, and some Cloudflare customer traffic saw elevated loss and higher latency.

    Packet lossHigh latency
    Trigger

    At 20:25 UTC Cloudflare's policy automation pushed a change, merged at 19:52 UTC, that removed the BGP announcements from Miami for a data center in Bogotá, Colombia, by deleting the prefix-list 6-BOG04-SITE-LOCAL from several export policy terms.

    Root cause
    Configuration change
    Component
    BGP routingBackbone network (WAN)
    Contributing factor
    No configuration tests
    Detection

    The network team began investigating unintended route advertisements from Miami at 20:40 UTC, and an incident was raised at 20:44 UTC.

    Remediation
    • A network operator reverted the bad configuration change on the Miami router by hand
    • Paused the automation for the router so it could not run again
    • Reverted the triggering change in the network automation code repository
    • Unpaused the automation on the Miami router after confirming it ran without the routing policy bug
    Action items
    • Patch the failure in the routing policy automation that caused the leak
    • Add BGP community-based safeguards that reject routes received from providers and peers on external export policies
    • Add automatic routing policy evaluation to the CI/CD pipelines that looks for empty or erroneous policy terms
    • Detect problems in network configurations and the effects of automated changes earlier
    • Validate routing equipment vendors' implementations of RFC9234 before rolling out BGP roles and the Only-to-Customer Attribute
    • Encourage long-term adoption of RPKI Autonomous System Provider Authorization (ASPA)
    Lessons

    Removing only the prefix lists from export policy terms left terms that were too permissive, because a match on route-type internal accepts IBGP routes as well. Cloudflare states that route leaks are easy to cause by accident and that RFC9234 is the only way, independent of routing policy, to prevent route leaks caused at the local AS.

    View case
  2. 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
  3. 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 3 cases involve Backbone network (WAN) and BGP routing. 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 cause1

Configuration change3 cases

Component
Backbone network (WAN)3BGP routing3Interior routing (IGP)2
Contributing factor
Excessive blast radius2No configuration tests2Unverified assumption1Harmful manual action1Ineffective rollback1
Organisation
Cloudflare1Microsoft Azure1OVHcloud1
  1. IL-0394 A Cloudflare router in Miami leaked IPv6 BGP routes to peers and providers for 25 minutes, congesting the backbone
    Cloudflare2026
  2. IL-0225 An IGP purge command made every Microsoft WAN router recompute routes, causing global latency, timeouts and packet loss
    Microsoft Azure2023
  3. IL-0228 IPv4 routing across OVHcloud's global network broke after a router change put the full internet routing table into OSPF
    OVHcloud2021