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Red Hat OpenDaylight Product Guide

Red Hat OpenStack Platform 10

Overview of Red Hat OpenDaylight

OpenStack Documentation Team


This guide provides a high level overview of the Red Hat OpenDaylight environment.


Red Hat OpenStack Platform 10 introduces a technology preview of the OpenDaylight software-defined networking (SDN) controller, integrated into the platform. OpenDaylight is an open, flexible, and modular SDN platform that can be used for various tasks in your Red Hat OpenStack environment.

The Red Hat OpenDaylight solution provides a smooth transition to software-defined networking for both service providers and traditional data center operators who are running Red Hat OpenStack Platform. It combines carefully selected services and thoroughly tested packages that will help you to set up a lean and stable OpenDaylight solution.

This document introduces Red Hat OpenDaylight on Red Hat OpenStack Platform, configured as an OpenStack SDN controller based on the NetVirt application.


OpenDaylight does not represent an independent Red Hat product and therefore is only provided as an integrated part of the Red Hat OpenStack Platform.


For more information on the support scope for features marked as technology previews, see Technology Preview Features Support Scope.

Chapter 1. OpenDaylight Introduction

1.1. What can I use OpenDaylight for?

OpenDaylight, hosted by the Linux Foundation, provides an open, modular and flexible SDN platform. It is composed of a number of different projects that can be combined together into a solution that meets the requirements of a given scenario, and can, therefore, cover many different use-cases.

To learn more, visit this OpenDaylight website, where you can find further information on various uses of OpenDaylight.

Red Hat’s OpenDaylight focuses on network control and virtualization. OpenDaylight is co-engineered with the Red Hat OpenStack Platform and used as a backend service for OpenStack Networking (neutron) to provide the networking infrastructure for your Red Hat OpenStack cloud.

1.2. Why use OpenDaylight with Red Hat OpenStack?

1.2.1. True SDN platform

Due to its software architecture, OpenDaylight serves as a multi-protocol, modular and extensible platform. As next generation network designs and standards emerge, and while SDN and NFV frameworks are evolving, OpenDaylight provides the needed flexibility to support the growing business, applications and network needs. The SDN controller approach is particularly suitable for organizations for whom the network is their main business driver. A networking solution that “just works” is not enough for such organizations, because they need a robust, but flexible at the same time, design that satisfies diverse use-cases and is able to scale as their business grows.

Furthermore, OpenDaylight leverages a large community and ecosystem which we believe is key to keep it relevant and innovative, today and in the future.

1.2.2. Standard-based with an open approach

OpenDaylight offers a model-driven approach to networking, which is all based on public APIs and protocols such as RESTCONF and YANG.

OpenDaylight is a crucial component in today’s virtualization stack, as well as a key for customers who want to deploy a fully open-source solution and avoid possible vendor lock-in.

1.2.3. Enhanced Cloud Networking

OpenDaylight provides support for common OpenStack network virtualization requirements, while ensuring multi tenancy, security and isolation. Some feature highlights include:

  • Distributed L2 networking using VLANs or overlays (VXLAN)
  • Distributed L3 forwarding
  • Dynamic IP address assignment, with support for overlapping IPs across tenants
  • Security Groups (per VM Access Control Lists)
  • NAT and Floating IPs

1.2.4. Interaction with physical fabric

While this version of Red Hat OpenDaylight within Red Hat OpenStack Platform 10 is still limited to virtual (overlay) network management only, future versions will add support for various aspects of physical (underlay) network control and management. This could provide customers with more capabilities, as well as with enhanced monitoring and troubleshooting tools across the end-to-end network path, be it virtual or physical.

1.2.5. SDN for NFVi

Cloud Service Providers (CSPs) deploying NFV are seeking a robust and open-source SDN solution as part of the Network Functions Virtualization Infrastructure (NFVi) layer. While Red Hat OpenDaylight with Red Hat OpenStack Platform 10 lays the foundation for NFV, future versions will add more support for NFV-specific features such as accelerated datapath connectivity and service function chaining (SFC).

Chapter 2. Understanding basic concepts

2.1. How does network virtualization work?

In the physical world, servers are mutually connected by physical Ethernet switches and cables. Each of them has a unique IP address and can either communicate directly or through IP routers. To access resources outside the server domain, communication goes through external gateways to external servers that are protected from any unwanted communication by firewalls. In most cases, servers in different domains cannot talk to each other directly, unless such communication is specifically established.

Figure 2.1. Physical networks

Physical networks

When using server virtualization, it is necessary to provide a similar networking strategy for virtual machines (VMs). In a virtualized environment, multiple independent VMs from different domains may run on the same physical server simultaneously, and VMs from the same domain may run on different physical servers. The virtual compute loads still require similar connectivity and security support as they would have in physical devices. Security becomes even more important when compute loads from different domains are hosted on the same server. Furthermore, virtual devices from different domains may even use the same, overlapping, private IP addresses.

Figure 2.2. Compute and Network virtualization

Compute and Network virtualization

Networking support for virtual compute resources is referred to as network virtualization, and is a common problem solved by Software-defined Networking (SDN) controllers. These environments can function independently from each other using tenant isolation.

2.2. What is software-defined networking?

Software-Defined Networking (SDN) is an approach for dynamically programming networks, including the ability to initialize, change and manage network behavior using open interfaces.

SDN often implies the physical separation of the network control plane from the forwarding plane such that a control plane may control several devices. The component that implements the SDN control plane is called SDN controller.

Figure 2.3. Functions of the SDN controller

Functions of the SDN controller

To make SDN work, there must be well-defined interfaces both between higher level management and orchestration systems and the SDN controller (northbound APIs) as well as between the SDN controller and data plane elements (southbound APIs).

SDN has broad applicability to many use cases. One area in which SDN has proved essential is cloud computing in general, and OpenStack in particular. OpenStack provides the foundation to build a private or public cloud in which virtualized compute resources, together with required networking and storage, can be dynamically instantiated and destroyed as needed. This dynamic environment requires a programmable networking solution that is equally dynamic — in other words, OpenStack needs SDN.

Later, you will learn more about how OpenDaylight is used as an SDN controller for OpenStack.

2.3. What is network functions virtualization?

In addition to basic networking, OpenDaylight can also be used with OpenStack to support network functions virtualization (NFV).

Network Functions Virtualization (NFV) is a software-based solution that helps the Communication Service Providers (CSPs) move beyond the traditional, proprietary hardware to achieve greater efficiency and agility while reducing operational costs.

NFV virtualizes network functions (for example, firewalls and load balancers) so they can run on a general-purpose servers in a cloud-based infrastructure to provide more agility, flexibility, simplicity, efficiency, and scalability than legacy infrastructure, while also reducing costs and allowing greater innovation.

SDN and NFV perform complementary functions in a virtualized network. NFV supports the virtualization of complex network functions while SDN is used to perform basic networking, and forward traffic to and between network functions.

For more on NFV concepts, see the Network Functions Virtualization Product Guide.

Chapter 3. What are the components of OpenDaylight?

The typical OpenDaylight solution consists of five main components: the OpenDaylight APIs, Authentication, Authorization and Accounting (AAA), Model-Driven Service Abstraction Layer (MD-SAL), Services and Applications, and various southbound plug-ins. The following diagram picture shows a simplified view of the typical OpenDaylight architecture. In this chapter, the basic functionality of the main components will be described. However, a detailed description of particular OpenDaylight components is out of scope of this guide.

Figure 3.1. OpenDaylight Platform Architecture

OpenDaylight Platform Architecture

3.1. Authentication, Authorization and Accounting (AAA)

The platform also provides a framework for Authentication, Authorization and Accounting (AAA), and enables automatic identification and hardening of network devices and controllers.

3.2. OpenDaylight APIs

The northbound API, which is used to communicate with the OpenStack Networking service (neutron), is primarily based on REST. The Model-Driven Service Abstraction Layer (described later) renders the REST APIs according to the RESTCONF specification based on the YANG models defined by the applications communicating over the northbound protocol.

3.3. Services and Applications

The business logic of the controller is defined in Services and Applications. The basic overview of services and applications available with the Boron release can be found on the OpenDaylight Boron release web page. A more detailed view can be obtained from the Project list. The OpenDaylight project offers a variety of applications, but usually only a limited number of the applications is used in a production deployment.

3.4. Model-Driven Service Abstraction Layer

The Model-Driven Service Abstraction Layer (MD-SAL) is the central component of the Red Hat OpenDaylight platform. It is an infrastructure component that provides messaging and data storage functionality for other OpenDaylight components based on user-defined data and interface models.

MD-SAL, in MD-SAL based applications, uses the YANG models to define all required APIs, including inter-component APIs, plug-in APIs and northbound APIs. These YANG models are used by the OpenDaylight YANG Tools to instantly generate Java-based APIs. These are then rendered according to the RESTCONF specification into the REST APIs and provided to applications communication over the northbound protocol.

Using YANG and YANG Tools to define and render the APIs greatly simplifies the development of new applications. The code for the APIs is generated automatically which ensures that provided interfaces are always consistent. As a result, the models are easily extendable.

3.5. Southbound Interfaces and Protocol Plug-ins

Applications typically use the services of southbound plug-ins to communicate with other devices, virtual or physical. The basic overview of southbound plug-ins available with the Boron release can be found on the OpenDaylight Boron release web page. The Project list shows them in more details.

3.6. Red Hat OpenDaylight components

The Red Hat OpenDaylight solution (part of the Red Hat OpenStack Platform) consists of the five main parts, but the selection of applications and plug-ins is limited to a certain number only. The Controller platform is based on the NetVirt application. This is the only application currently supported by Red Hat. In the future releases, more applications will be added.

Most applications will only use a small subset of the available southbound plug-ins to control the data plane. The NetVirt application of the Red Hat OpenDaylight solution uses OpenFlow and Open vSwitch Database Management Protocol (OVSDB).

The overview of the Red Hat OpenDaylight architecture is shown in the following diagram.

Figure 3.2. Red Hat OpenDaylight architecture

OpenDaylight Operational Model

Chapter 4. How does OpenDaylight cooperate with OpenStack?

OpenStack Networking (neutron) supports a plugin model that allows it to integrate with multiple different systems in order to implement networking capabilities for OpenStack.

For the purpose of OpenStack integration, OpenDaylight exposes a single common northbound service, which is implemented by the Neutron Northbound component. The exposed API matches exactly the REST API of neutron. This common service allows multiple neutron providers to exist in OpenDaylight. As mentioned before, the Red Hat OpenDaylight solution is based on NetVirt as a neutron provider for OpenStack. It is important to highlight that NetVirt consumes the neutron API, rather than replacing or changing it.

The OpenDaylight plug-in for OpenStack neutron is called networking-odl, and is responsible for passing the OpenStack network configuration into the OpenDaylight controller. The communication between OpenStack and OpenDaylight is done using the public REST APIs. This model simplifies the implementation on the OpenStack side, because it offloads all networking tasks onto OpenDaylight, which diminishes the processing burden for OpenStack.

Figure 4.1. OpenStack and OpenDaylight Architecture

OpenStack and OpenDaylight Architecture

The OpenDaylight controller uses NetVirt, then configures Open vSwitch instances (which use the OpenFlow and OVSDB protocols), and provides the necessary networking environment. This includes layer 2 networking, IP routing, security groups, and so on. The OpenDaylight controller can maintain the necessary isolation among different tenants.

In addition, NetVirt is also able to control hardware gateways using the OVSDB protocol. A hardware gateway is typically a top of rack (ToR) Ethernet switch, that supports the OVSDB hardware_vtep scheme, and can be used to connect virtual machines with the actual physical devices.

Chapter 5. Overview of features supported with Red Hat OpenStack Platform 10

The following chapter lists the key features supported by OpenDaylight and Red Hat OpenStack Platform 10.

5.1. Integration with Red Hat OpenStack Platform Director

The Red Hat OpenStack Platform director is a toolset for installing and managing a complete OpenStack environment. Starting with Red Hat OpenStack Platform 10, director can deploy and configure OpenStack to work with OpenDaylight. OpenDaylight can run together with the OpenStack overcloud controller role, or as a separate custom role on a different node.

For more information, see the OpenDaylight and Red Hat OpenStack Installation and Configuration Guide.

5.2. L2 Connectivity between OpenStack instances

OpenDaylight provides the required Layer 2 (L2) connectivity among VM instances belonging to the same neutron virtual network. Each time a neutron network is created by a user, OpenDaylight automatically sets the required Open vSwitch (OVS) parameters on the relevant compute nodes to ensure that instances, belonging to the same network, can communicate with each other over a shared broadcast domain.

While VXLAN is the recommended encapsulation format for tenant networks traffic, 802.1q VLANs are also supported. In the case of VXLAN, OpenDaylight creates and manage the virtual tunnel endpoints (VTEPs) between the OVS nodes automatically to ensure efficient communication between the nodes, and without relying on any special features on the underlying fabric (the only requirement from the underlying network is support for unicast IP routing between the nodes).

5.3. IP Address Management (IPAM)

VM instances get automatically assigned with an IPv4 address using the DHCP protocol, according to the tenant subnet configuration. This is currently done by leveraging the neutron DHCP agent. Each tenant is completely isolated from other tenants, so that IP addresses can overlap.


OpenDaylight can operate as a DHCP server. However, using the neutron DHCP agent provides High Availability (HA) and support for VM instance metadata (cloud-init). Therefore Red Hat recommends to deploy the DHCP agent, rather than relying on OpenDaylight for such functionality.


Red Hat OpenStack Platform 10 only provides support for IPv4 tenant networks.

5.4. Routing between OpenStack networks

OpenDaylight provides support for Layer 3 (L3) routing between OpenStack networks, whenever a virtual router device is defined by the user. Routing is supported between different networks of the same project (tenant), which is also commonly referred to as East-West routing.

OpenDaylight uses a distributed virtual routing paradigm, so that the forwarding jobs are done locally on each compute node.


Red Hat OpenStack Platform 10 only provides support for IPv4 tenant networks.

5.5. Floating IPs

A floating IP is a 1-to-1 IPv4 address mapping between a floating address and the fixed IP address, assigned to the instance in the tenant network. Once a VM instance is assigned with a floating IP by the user, the IP is used for any incoming or outgoing external communication. The Red Hat OpenStack Platform director includes a default template, where each compute role has external connectivity for floating IPs communication. These external connections support both flat (untagged) and VLAN based networks.

5.6. Security Groups

OpenDaylight provides support for tenant configurable Security Groups that allow a tenant to control what traffic can flow in and out VM instances. Security Groups can be assigned per VM port or per neutron network, and filter traffic based on TCP/IP characteristics such as IP address, IP protocol numbers, TCP/UDP port numbers and ICMP codes.

By default, each instance is assigned a default Security Group, where egress traffic is allowed, but all ingress traffic to the VM is blocked. The only exception is the trusted control-plane traffic such as ARP and DHCP. In addition, anti-spoofing rules are present, so a VM cannot send or receive packets with MAC or IP addresses that are unknown to neutron. OpenDaylight also provides support for the neutron port-security extension, that allows tenants to turn on or off security filtering on a per port basis.

OpenDaylight implements the Security Groups rules within OVS in a stateful manner, by leveraging OpenFlow and conntrack.

Chapter 6. What hardware can I use with OpenDaylight?

Red Hat OpenDaylight works with the server hardware supported in Red Hat OpenStack Platform. You can use Red Hat Technologies Ecosystem to check for a list of certified hardware and software by choosing the category and then selecting the product version.

For a complete list of the certified hardware for Red Hat OpenStack Platform, see Red Hat OpenStack Platform certified hardware.

For more information on supported network adapters, see Network Adapter Feature Support for Red Hat Enterprise Linux.

Chapter 7. Where can I find more information about Red Hat OpenStack Platform and OpenDaylight?



For further information that is not covered in this document, see the OpenDaylight Boron documentation.

Red Hat OpenDaylight Installation and Configuration

For more information and detailed instructions on how to deploy OpenDaylight with Red Hat OpenStack using the Red Hat OpenStack Platform director, see the OpenDaylight and Red Hat OpenStack Installation and Configuration Guide.

Red Hat Enterprise Linux

Red Hat OpenStack Platform is supported on Red Hat Enterprise Linux 7.3. For information on installing Red Hat Enterprise Linux, see the corresponding installation guide at Red Hat Enterprise Linux Documentation Suite.

Red Hat OpenStack Platform

To install OpenStack components and their dependencies, use the Red Hat OpenStack Platform director. The director uses a basic OpenStack undercloud, which is then used to provision and manage the OpenStack nodes in the final overcloud. Be aware that you will need one extra host machine for the installation of the undercloud, in addition to the environment necessary for the deployed overcloud. For detailed instructions, see Director Installation and Usage.

For information on configuring advanced features for a Red Hat OpenStack Platform enterprise environment using the Red Hat OpenStack Platform director such as network isolation, storage configuration, SSL communication, and general configuration method, see Advanced Overcloud Customization.

You can also manually install the Red Hat OpenStack Platform components, see Manual Installation Procedures.

NFV Documentation

For more details on planning your Red Hat OpenStack Platform deployment with NFV, see Network Function Virtualization Planning Guide.

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