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OVN-Kubernetes Network Topology

OVN-Kubernetes uses interconnect mode, a distributed control plane architecture. The network topology is distributed across zones; each node is a zone of its own.

OVN-Kubernetes Network Topology - Distributed (Interconnect)

The interconnect architecture in OVN-K looks like this today (each node is a zone of its own):

ovn-kubernetes-distributed-topology

On each node we have:

  • node-local-switch: all the logical switch ports for the pods created on a node are bound to this switch and it also hosts load balancers that take care of DNAT-ing the service traffic
  • ovn-cluster-router: it's responsible for routing traffic between the node switch and the gateway router (since each zone is a single node it behaves like a local router; there is no need for a distributed setup)
  • join-switch: connects the ovn-cluster-router to the gateway router (since each zone is a single node it behaves like a local switch; there is no need for a distributed setup)
  • node-local-gateway-router: it's responsible for north-south traffic routing and connects the join switch to the external switch and it also hosts load balancers that take care of DNAT-ing the service traffic
  • node-local-external-switch: connects the gateway router to the external bridge
  • transit-switch: distributed across the nodes in the cluster and responsible for routing traffic between the different zones.

FIXME: This page is lazily written, there is so much more to do here.