Explanation and Overview

Network Orchestration, also known as Software-defined networking (SDN) Orchestration is the process of automatically programming the behaviour of the network so that the network smoothly coordinates with the hardware and the software elements to further support applications and services.^[1]

[1] (2020) Medium.com (https://medium.com/@datapath_io/what-is-network-orchestration-744cac97847c)

Introduction

In the cloud, you want to create a virtual datacentre with firewalls and load balancers. Traditional networking couldn’t virtualise the firewalls and load balancers, as they were all physical appliances. They could cope with the requirement by implementing different VLANs and some sort of partitioning, but that solution was not scalable and could not comply with a high frequency of changes that the cloud was demanding. Soon, businesses realized that NFV (Network Function Virtualization) was the solution that could virtualize the firewalls and load balancers.

The cloud drove the networking industry into virtualization and towards a way for central control. Soon, we started seeing the new virtual networking software coming up from proprietary vendors and open-source providers.

This module will consider the several layers of software-defined networks:

Network Control
Network Virtualization
Cloud and Virtual Management
Orchestration, Management, Policy
Network Data Analytics

Network Control

A network controller is similar to a single brain that can manage a network. It consists of multiple physical or virtual switches and routers. A network controller knows all endpoints (virtual machines, physical hosts, any device with a MAC address connected to the network) in the network, and programs the underlying network devices (hardware devices of virtual switches) to enable communication between endpoints.

Network controller

The Network Controller Can Manage Virtual or Hardware Switches/Network Devices

As a more practical example for network engineers, you can imagine a network controller as a supervisor module of a chassis-based switch. A supervisor module programs the switch line cards and fabric modules (crossbars) to allow communication between line cards. In a network, an SDN controller’s role is similar to a supervisor engine in a chassis-based switch, but it is not limited to a specific number of switches (line cards).

Network Virtualization

Network virtualization is about creating virtual networks on top of physical networks, also knows as an overlay network.

Network virtualisation

Overlay Networks Are Virtual Networks on Top of Physical Networks, Built Using Encapsulation and Tunnels

Overlay networking is mainly based on encapsulation technologies. The endpoints send data packets to each other with addresses that may not be routable in an underlying network. The overlay hosts encapsulate the original data packets into other packets (such as GRE or VXLAN) and send the packets to a physical underlay network towards the destination host. The destination host decapsulates the packet and delivers it to the endpoint.

Cloud and Virtual Management

Cloud platforms such as OpenStack, open container orchestration, the CORD project and VMware vSphere can drive the network control layer. Such cloud platforms require you to set up virtual networks, create virtual network functions or perform service insertion. Cloud platforms communicate directly with the network controller to perform their required tasks.

Cloudvirtualmanagement Cloud and Virtual Management Layer Communicates with Network Controllers

As a simple example, imagine that you are creating a new tenant (project) in OpenStack. You need to create a new virtual network for five virtual machines of this tenant to be able to communicate with each other. As a cloud platform, OpenStack will be able to call the required APIs on network controllers such as OpenDaylight to create a virtual tenant network.

OpenStack only requests the network controller (in this case OpenDaylight) to create a virtual network. It is the network controller’s job to translate this request into networking tasks and find out which network devices (virtual or physical) are in the transit path between the five virtual machines. After it finds the relevant network devices, it will start programming their forwarding tables using the southbound protocols (such as OpenFlow, SNMP, NETCONF or CLI).

Orchestration, Management, Policy

The orchestration, management and policy layer is where most NFV (Network Function Virtualization) management platforms are operating. Orchestration tools such as Open Source MANO, Open Security Controller, Akraino Edge Stack, ONAP, and Apache ARIA TOSCA are automation platforms that can create virtual network functions and infrastructure.

Orchestration Platforms Communicate with Network Controller and Cloud Management Layers

Such orchestration platforms are mainly used for automation and batch creation of a service.

For example, the Open Security Controller, which is a software-defined security platform, can enforce security in a network. It will communicate with virtualization management platforms to create virtual firewalls or virtual routers and ask cloud virtualization platforms to create the required virtual machines for these new virtual firewalls (aka virtual network functions, or VNFs).

The Open Security Controller also communicates with the network controller to create service insertion. For example, it can tell OpenDaylight to create a policy to ensure that all traffic to a database server is always sent to a virtual IDS (Intrusion Detection System) before hitting the database server.

Network Data Analytics

Network data analytics utilizes new technologies and tools such as Big Data, machine learning, and AI to provide knowledge about the network. Such projects and tools are different from the traditional monitoring and data gathering tools that most organizations use on a day-to-day basis.

Examples of Network Data Analytics are:

SNAS(formerly OpenBMP, stands for Streaming Network Analytics System)
SNAS is a framework to collect, track and access tens of millions of routing objects (routers, peers, prefixes) in real-time. OpenBMP was created to analyse BGP (Border Gateway Protocol) and implemented IETF BMP (BGP Monitoring Protocol). OpenBMP converted to SNAS to provide more functions and use cases for a networking analytics platform.
PNDA(Platform for Network Data Analytics)
PNDA is a Big Data analytics tool with multiple networking use cases and integrations with network controllers such as OpenDaylight or log management platforms such as Logstash and SNAS.
Acumos AI
Acumos AI is The Linux Foundation’s artificial intelligence platform, with multiple use cases. It’s a modular platform that can access data from different sources. Developers can build AI applications on top of Acumos to analyse the data, find patterns and predict facts. Acumos has an open marketplace where developers upload their AI applications. Acumos gets integrated with ONAP (Open Networking Automation Platform) and OpenDaylight as data sources, allowing developers to create AI networking applications.

Challenges

The challenges can be found here.

Resources

Network Control		OpendayLight ONOS Tungsten Fabric
Network Virtualization		Kubernetes Katran Multipass
Cloud and Virtual Management		OpenStack
Orchestration, Management, Policy		Mano ONAP
Network Data Analytics		SNAS PNDA

	https://www.my-mooc.com/en/mooc/introduction-to-open-source-networking-technologies/
Introduction to Network Services Orchestrator - the single API and CLI for your network	Introduction to Network Services Orchestrator - the single API and CLI for your network
Network Orchestration made simple	Network orchestration made simple
Cisco DevNet Network programming	Cisco DevNet
Software-Defined Networking and Network Virtualization	SDN basics Introduction to SDN (Software-defined Networking) Software-Defined Networking (SDN) Introduction Network Virtualization
	https://www.opennetworking.org/wp-content/uploads/2014/10/openflow-switch-v1.5.1.pdf
	untangle_get_started_with_sd_wan_e_book.pdf Installing-Untangle-SD-WAN-Router-on-VMware-ESXi