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Navigating OpenStack network virtualization: A closer look at OVN and OVS

Navigating OpenStack network virtualization: A closer look at OVN and OVS

OpenStack deployments heavily rely on efficient network virtualization solutions to enable scalability and flexibility. In this blog, we’ll delve into the relationship between Open Virtual Networking (OVN) and Open vSwitch (OVS) within the OpenStack ecosystem. We’ll explore their distinctive functionalities and their separation. Let’s briefly recap the core aspects of OVN and OVS and their roles within the OpenStack ecosystem. 

Open vSwitch (OVS) 

OVS serves as a virtual switch implementation, providing network switching capabilities specifically designed for virtualized environments. Acting as a software-based switch, OVS enables the creation and management of virtual ports, bridges, and tunnels. With support for multiple protocols and features, OVS offers a flexible and extensible solution for network virtualization. 

Open Virtual Networking (OVN) 

OVN serves as a network virtualization abstraction layer built on top of OVS. It offers logical network components, including virtual networks, routers, and security groups. OVN simplifies the definition and management of network connectivity and policies within virtualized environments. By leveraging the switching capabilities of OVS, OVN implements overlay networking to enable advanced features like routing, access control, and distributed load balancing. 

Integration and functionality 

OVN and OVS function collaboratively, with OVN leveraging OVS as the underlying network infrastructure to implement its logical abstractions and overlays. OVN provides higher-level functionality and management capabilities, enabling administrators to define and orchestrate virtual networks. Meanwhile, OVS handles the actual forwarding of packets based on the rules and configurations defined by OVN. 

The integration of OVN and OVS empowers the creation of logical networks with rich connectivity features, including routing, access control, and distributed load balancing. The logical networks defined in OVN are seamlessly translated into OVS configurations and rules to facilitate efficient network traffic flow and isolation. 

The advantages of OVN in OpenStack 

OVN is often recommended as the preferred network virtualization solution within OpenStack deployments. It offers native integration and features specifically tailored to OpenStack environments. OVN simplifies the configuration and management of virtual networks, abstracting the complexities of OVS and providing a user-friendly interface. By leveraging OVN, administrators can streamline the setup and maintenance of virtual networks, enhancing the efficiency and scalability of their OpenStack deployments. 

The transition: ML2/OVN as the recommended mechanism driver 

Red Hat has made a significant shift in its OpenStack deployments, choosing ML2/OVN as the default mechanism driver for new installations from RHOSP 15.0 onwards. Consequently, the ML2/OVS mechanism driver has been deprecated since RHOSP 17.0. Over the course of several releases, Red Hat has been gradually replacing ML2/OVS with ML2/OVN. While the deprecated ML2/OVS driver still receives bug fixes and support throughout the RHOSP 17 releases, new feature development primarily occurs in the ML2/OVN mechanism driver. 

Future outlook: Transitioning to ML2/OVN 

In RHOSP 18.0, Red Hat plans to completely remove the ML2/OVS mechanism driver and discontinue its support. If your existing RHOSP deployment utilizes the ML2/OVS driver, it’s crucial to start evaluating the advantages and feasibility of migrating to the ML2/OVN mechanism driver. Migration is supported in RHOSP 16.2 and will continue to be supported in RHOSP 17.1. 

Timing the upgrade 

Determining the ideal timing for an upgrade depends on various factors, including your business requirements and the status of ongoing improvements in the ML2/OVN offering. For instance, if you anticipate the need for security groups logging (planned for a future RHOSP release), it might be advisable to plan your migration accordingly. Stay informed about updates and enhancements to ensure an optimal transition experience. 

Let’s continue the conversation 

If you’re interested in discussing your experiences with OVS and OVN or have any questions, we invite you for a conversation. Together, we can navigate the intricacies of network virtualization and uncover the best strategies for your OpenStack deployments. In addition, we offer a free OpenStack health check, where we can check whether your OpenStack environment is healthy and ready for the migration. Give us a call or request your OpenStack health check directly through the following link:  

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