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Scenario #164
Networking
K8s v1.19, On-premise
IP Overlap Leading to Communication Failure Between Pods
Pods failed to communicate due to IP address overlap caused by an incorrect subnet configuration.
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What Happened
The pod network subnet overlapped with another network on the host machine, causing IP address conflicts and preventing communication between pods.
Diagnosis Steps
- 1Verified pod IPs using kubectl get pods -o wide and identified overlapping IPs with host network IPs.
- 2Checked network configuration on the host and discovered the overlapping subnet.
Root Cause
Incorrect subnet configuration that caused overlapping IP ranges between the Kubernetes pod network and the host network.
Fix/Workaround
• Updated the pod network CIDR range to avoid overlapping with host network IPs.
• Restarted the Kubernetes networking components to apply the new configuration.Lessons Learned
Pay careful attention to subnet planning when setting up networking for Kubernetes clusters to avoid conflicts.
How to Avoid
- 1Use a tool to validate network subnets during cluster setup.
- 2Avoid using overlapping IP ranges when planning pod and host network subnets.