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Why your KubeVirt VMs can't move between clusters — and how EVPN fixes it
OpenPERouter uses Kubernetes CRDs to manage EVPN/VXLAN overlays, enabling KubeVirt VMs to migrate across clusters without requiring manual network configuration or change tickets.
What: The solution abstracts network configuration by defining Underlay, L2VNI, and L3VNI resources in Kubernetes, allowing teams to stretch L2 domains and isolate migration traffic on-demand.
Why it matters: This shifts VM mobility from a manual, ticket-heavy networking task to a declarative platform operations workflow, making it feasible to perform live migrations between clusters without vendor-specific hardware or long wait times.
Takeaway: Review the OpenPERouter example configurations for implementing dedicated migration networks and stretched L2 domains: https://openperouter.github.io/
Deep dive
- Cross-cluster VM migration requires a stretched Layer 2 network to maintain IP and MAC addresses.
- Standard Kubernetes networking does not handle cross-cluster Layer 2 adjacency.
- EVPN/VXLAN overlays allow traffic to traverse different physical segments as if they were on the same switch.
- OpenPERouter enables management of these network fabrics via standard K8s Custom Resource Definitions (CRDs).
- Dedicated migration networks isolate multi-gigabyte memory state transfers from application traffic.
- Whereabouts can be used for cross-cluster IPAM to prevent address conflicts during migration.
Decoder
- EVPN (Ethernet VPN): A BGP-based control plane for VXLAN that allows Layer 2 connectivity over a Layer 3 infrastructure.
- VXLAN (Virtual Extensible LAN): A network virtualization technology that tunnels Layer 2 Ethernet frames over Layer 3 UDP/IP packets.
- VNI (VXLAN Network Identifier): A 24-bit identifier used to distinguish between different virtual network segments in a VXLAN overlay.
- CRD (Custom Resource Definition): A Kubernetes extension that allows users to define their own resource types and manage them using standard kubectl commands.
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