OpenStack's networking component, Neutron, was built with Software-Defined Networking (SDN) in mind. Thanks to its modular, plugin-based architecture, OpenStack can integrate with a wide range of SDN solutions to provide powerful, scalable, and secure virtual networking.
Open vSwitch (OVS)
Open vSwitch (OVS) is the foundational virtual switch in many OpenStack deployments. It is the default backend for Neutron's ML2 plugin and supports overlay networking using VXLAN, GRE, or Geneve.
Integration with OpenStack: OVS runs on each compute node to manage VM network interfaces and tunnel traffic between nodes.
Benefits:
- Tenant isolation via VLAN or VXLAN
- Automated network creation
- Foundation for advanced SDN layers
OVN (Open Virtual Network)
OVN is an SDN controller framework that works with OVS to provide a full-featured control plane for virtual networking.
Integration with OpenStack: Through the networking-ovn ML2 plugin, OVN replaces traditional Neutron agents.
Benefits:
- Distributed routing for better performance
- Reduced reliance on centralized agents
- Scales well in large deployments
Tungsten Fabric (OpenContrail)
Tungsten Fabric is an open-source SDN solution with a powerful centralized controller and distributed vRouter on compute nodes. It originated from Juniper Networks and supports rich networking features.
Benefits:
- Deep network segmentation and multi-tenancy
- Built-in analytics and security policy engine
- BGP EVPN support for physical integration
OpenDaylight (ODL)
OpenDaylight is a modular SDN controller that supports OpenFlow, NETCONF, BGP, and more.
Benefits:
- Centralized SDN brain for full-stack network control
- Flexible policy-based automation
- Suited for NFV and telco environments
Dragonflow
Dragonflow is a distributed SDN controller developed specifically for OpenStack. It eliminates centralized network nodes by running control logic on each compute host.
Benefits:
- Local routing and DHCP for low latency
- Scalable with no single point of failure
- OpenStack-native design and simplicity
Other Noteworthy Mentions
- Midonet: A distributed SDN platform that replaces Neutron agents with a custom control plane.
- Calico: A layer 3 networking solution using BGP and iptables without overlays.
- Vendor Solutions (NSX, Cisco ACI): Proprietary SDN platforms with deep integrations.
Benefits of SDN in OpenStack
1. Network Segmentation & Security — Isolate tenant traffic, microsegmentation, distributed firewalls.
2. Automation & Agility — Rapid provisioning via APIs, infrastructure-as-code, dynamic updates.
3. Scalability — Thousands of tenants with VXLAN, distributed control for efficient routing.
4. Performance Optimization — Distributed routing improves east-west traffic.
5. Multi-Tenant Cloud Use Cases — SaaS providers, dev/test/prod environments, telco NFV.
SDN has revolutionized networking in OpenStack, enabling tenant isolation, dynamic provisioning, distributed routing, and more.