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Weaving the Fabric: EVPN overlays for multi-cluster KubeVirt deployments#

FOSDEM 2026 digest Program Core pick 31 January – 1 February 2026

Abstract Slides Recording

Miguel Duarte, Federico Paolinelli (Red Hat)

  • Why: The companion session to OpenPERouter, focused on the fabric problem: stretched L2 for cross-cluster VM live migration, DR, and hybrid cloud — done with open components rather than a proprietary DCI.
  • What: Multi-cluster KubeVirt L2/L3 overlays built from OpenPERouter + KubeVirt + any bridge-based CNI (OVS-CNI, bridge-cni, macvlan, ipvlan). L2VNI stretches a Layer 2 domain across clusters with a distributed anycast gateway and live-migration support; L3VNI (EVPN Type 5) gives VMs direct routed ingress from provider networks — no Kubernetes Services, no NAT.
  • How: Declarative CRDs configure VTEPs (Underlay CRD with vtepcidr), MAC VRFs (L2VNI), and routing domains (L3VNI); FRR advertises Type 2 (MAC/IP) and Type 5 (prefix) routes. VMs attach via a bridge on the host defined with a standard NetworkAttachmentDefinition. A public demo repo and asciinema recording accompany the talk.
  • Where applicable: Multi-cluster or multi-site KubeVirt estates needing VM mobility, legacy broadcast/multicast workloads, or direct fabric ingress into VMs. Requires an EVPN-capable underlay and OpenPERouter on each participating cluster — this is a design-patterns talk on top of the architecture session above.