CUDN with BGP EVPN

Cluster User Defined Networks (CUDN) with BGP EVPN extends OVN-Kubernetes user-defined networks beyond the cluster boundary. By using BGP EVPN as the interconnect, external routers can participate in the overlay network, enabling seamless Layer 2 and Layer 3 connectivity between workloads inside OpenShift and services outside the cluster.

Official documentation:

• User-defined networks

Tested with:

Component	Version
OpenShift	v4.22
VyOS	TBD

Architecture

The lab environment runs on a single Hetzner bare-metal server using hetzner-ocp4 to provision OpenShift 4.22 via libvirt/KVM. A VyOS virtual machine acts as the BGP edge router peering with the OVN-Kubernetes cluster network.

Content

• Networking

• User Defined Networks

• Services & Routes

• Multus

• Network Policy

• Router sharding

• Gateway API

• Egress IP

• Kubernetes iptables chains

• LLDPd

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2026-10-16 2026-10-16 Contributors: