SDN, SD-WAN, NFV and VFN- Choose the Network Solution That Best Suits You
Last decade has seen the networking industry transforming itself. With the advent and exponential growth of applications like Social Media, Video on Demand and Cloud deployments, the complexity of the networks has increased exponentially.
Any decent sized networks contain multitude of network services deployed on proprietary hardware from variety of vendors.Each of the network service implement a different interface for management, troubleshooting and visualization.
In this environment, introduction of new network service (typically with a new vendor) or updation to existing service requirements, requires complex manipulations to the production environment. This introduces risk and delay to introduction of new business requirement.
As the network services are implemented on proprietary hardware, the refresh cycles for hardware are expensive and disruptive. Also, every network service follows independent refresh cycle complicating the task of managing the upgrades.
As the importance of networks increase due to adoption of newer business practices, there is a demand for faster software upgrades, simplified operations and quick adaptation of network policies for new business requirements.
These issues have forced network industry to look for a different approach of implementing the network services. Virtualization of network functions, automation of the network and End-to-End visualization for fault detection and predictive actions are expected by the networking industry.
This is a paradigm shift in the way networking services are implemented and deployed. This has led to a mushrooming of terms, which can sound daunting. Here we help you understand four very common ones:
Software-Defined Network (SDN):
At the very core the function of SDN is to enable the agility in the networks by allowing the networks to be programmable. This allows for automation of networks which can be adapted dynamically without the need for manual intervention.
The intelligence built into the networks allows for minimized lead time between the planning and implementation.
In order to enable the programmable nature of networks, the legacy monolithic network is logically split into:
- Programmable Control Plane: The control plane’s primary function is to program the Forwarding Plane based on the inputs received from the various sources like Business Applications, Analytics Systems, Rules and Policy Engine etc. The inputs are typically received using REST APIs enabling integration with variety of tools used in the enterprise. The Control Plane can be integrated with various analytics and data visualization tools to provide end to end view of the network.
- Programmable Forwarding Plane: The Forwarding Plane’s main job is to process the packet while applying the networking logic and rules programmed by the Control Plane. Openflow is an example of protocol which can be used to control the Forwarding Plane. However, as the applicability of the SDN architecture concepts expanded, additional protocols and APIs were defined between Control Plane and Forwarding Plane. In fact based on the use cases, it is possible to implement Control Plane and Forwarding Plane as part of the same VM or Container.
Network Automation using Orchestration and network abstraction/overlay helps in further improving the agility of the network.
Orchestration will help to automate creation/destruction of services and reconfiguration of the network services based on the dynamic requirements. Network Automation is the integral part of the SDN architecture.
2. Software Defined Wide Area Network (SD-WAN):
Enterprise WANs are costly, inflexible and very complex to manage. Any enterprise‘s network demands greater agility and efficiency. With SD-WAN you can address these typical issues in traditional WAN network.
SD-WAN is a specific example of expanding scope of NFV/SDN from the traditional data centre applications to WAN network.
SD-WAN technology provides the capability of creating a completely flexible and application aware overlay network comprising of one are many access network technologies e.g. MPLS, Broadband.
In addition to traditional WAN based network services, the SD WAN solution includes orchestration platform with Graphical User Interface (GUI) based management system.
The unified management of branch network devices and applications allow for end-to-end view of the network and unified. That, by itself, means the WAN is flexible in a way that it likely wasn’t before.
The Devices and VNFs (either in private or public cloud) create an overlay network which is used to apply centralized policy to the forwarded traffic independent of the underlying hardware and networking protocols. The simplified centralized operations and orchestration system allow for simplified operations.
3. Network Function Virtualisation (NFV):
As the operators and vendors started visualizing the Network Functions as Virtual it became necessary to define a framework for implementation and deployment of network services in order to allow for maximising the functionalities and benefits of Virtualization by allowing ease of interoperability.
The NFV architecture, first laid out by the European Telecommunications Standards Institute (ETSI), defines a framework and specific set of interfaces to deploy and manage virtual network functions. This allows a deployment of a single unified network consisting of multiple VNFs implemented by different vendors and managed and configured by a single software APIs application and/or Orchestrator without compromising on the flexibility and agility expected due to virtualization.
The NFV Architecture is Structured over three layers — VNFs, NFVI and NFV-MANO — NFV lays down protocols to deploy and secure VNFs which are agnostic of hardware platforms. The VNF refers to the software based network functions that are typically deployed as virtual machines.
The NFVI refers to the infrastructure on which the VNFs are deployed i.e., all the hardware and networking deployed to support the VNF software over virtual machine(s).
The NFVI framework and interfaces allows the on-demand creation/destruction of VNFs, allow the VNFs to be moved around to different hardware and to different locations without disruption based on dynamic network conditions (e.g., load) or based on changing business environment (e.g., addition of new service to the network).
The NFV-MANO layer is responsible for the orchestration and management of the software functions.
4. Virtualised Network Functions (VNFs):
Network Function refers to a service provided by an element in the network for the processing the packet. Examples of network functions include Firewall, load balancer etc. Traditionally, these were implemented on proprietary hardware.
With recent advances in virtualization technology and also due to external business drivers, number of NF vendors and customers are migrating the services to virtualized platforms in order to take advantage of general purpose hardware.
Generally speaking, any network function running on a virtual platform can be called a VNF. As the VNFs are virtualized, the VNFs are able to be upgraded and modified compared to hardware based network functions which face obsolescence.
In the SDN/NFV Architecture, VNF is one of the building blocks handling a particular aspect of the network service.
The VNFs implement the programmable APIs (with entities like EMS, Orchestrators, Business Applications etc) defined in the NFV architecture to control its functions.
The SDN/NFV based VNFs allow for easy integration with NFV complaint Orchestrators, Element managers and NFVI (e.g., openstack).
