OVN

1. Open vSwitch (OVS)
   1. OVS dataplane
2. Open Virtual Network (OVN)
   1. Northbound DB
   2. OVN-Northd
   3. Southbound DB
   4. OVN controller
   5. OVN dataplane

Open vSwitch (OVS)

• L2 switch with OpenFlow support
• requires L3 agent on a separate mode for L3 forwarding ⇒ bottleneck
• OVSDB: configuration protocol
  • JSON RPC
  • create bridge, attach interface
  • ovsdb-server
• OpenFlow: data plane configuration
  • ovs-vswitchd
• packet handle
  • no flow entry: kernel sends packet to ovs-vswitchd who then caches flow in kernel
  • flow entry available: fast path in kernel
• OVS agent:
  • Python

OVS dataplane

Open Virtual Network (OVN)

• written in C
• ARP suppress + ARP spoofing and imposing destination
• functions
  • distributed L2/L3 for IPv4/IPv6
  • overlay support
  • ACL
  • NAT
  • DHCP
  • load-balancing
• hypervisors: KVM, Xen, Hyper-V, containers, DPDK

Northbound DB

• logical network, no info about physical network
• logical switches, routers, ports, ACL

OVN-Northd

• translates contents of Northbound DB into OpenFlow in Southbound DB
• operates logical entities

Southbound DB

• logical OpenFlow data from OVN-Northd
• data from hypervisors

OVN controller

• translates logical OpenFlow into physical entities (e.g., reference to other hypervisor → tunnel to hypervisor)

OVN dataplane

• Kernel Connection tracking (conntrack) for stateful FW is more performant than bridge with iptables