A gentle introduction to SD-WAN
You guessed right!
This article is about computer networks, particularly SD-WAN!. If you don’t already know about computer networks, don’t fret! We would address the fundamentals necessary for you to have a full grasp of the subject. SD-WAN is the acronym for Software-Defined Wide Area Networks. For you to have a full grasp, there are a few subjects you need to understand, they include:
- Local Area Networks (LAN)
- Wide Area Networks (WAN)
- Traditional Networking
- Software-Defined Networking
Following the invention of computers, it was realized that there was no direct communication or interaction between a user and the computer, thus users experienced very long delays between submission of jobs and receipt of output results. To tackle this challenge, an interactive terminal was created where users were connected to a mainframe computer via a low-speed data line. This birthed computer networks and over time computer networks have evolved from just communicating with a few devices to thousands of interconnected devices. Computer networks can be categorized into several types based on the geographic area and number of computers they cover; the four most popular include:
- Personal Area Network (PAN)
- Local Area Network (LAN)
- Wide Area Network (WAN)
- Metropolitan Area Network (MAN)
For this article, however, the focus would be on LAN and WAN. LAN is a group of interconnected computers (usually less than 5000) contained within a small geographical zone (1 km to 10 km). Although LAN-connected devices can use Ethernet and/or Wifi to connect devices within a network, they usually use a single internet connection. Think of it more like having to stay with your extended family within a fairly small area with the patriarch (oldest male) still presiding over family functions. A LAN comprises cables, access points, switches, routers, and other components that enable devices to connect to internal servers, web servers, and other LANs via wide area networks. Typically, a WAN is a computer network that is connected over a large geographical area. It most times is an interconnection of LAN networks. WAN can be connected in several ways, some of the most common include leased lines, VPNs, or IP tunnels.
Computer networks were made possible through the use of physical devices and overtime these improved, there was a proliferation of routers, switches, hubs, and other networking devices. Traditionally, the networks were built with the Ethernet switches arranged in a tree-like structure with each device having a local data and control plane. The network is managed through these aforementioned planes; in the control plane, forwarding and routing decisions are made while the data plane is where the commands (decisions) in the control plane are executed. Device configuration changes are made through the data plane, thus each device needs to be connected individually. As networks grew with the prevalence of big data, so did the cost and complexity of management.
Software-Defined Networking provides a way to improve the management of network architectures as it decouples the network control logic from the devices. It uses software-based controllers and Application Programming Interfaces (APIs) to communicate with network devices and direct traffic on a network. Software-Defined Networking architecture is composed of three main parts:
- Applications: The application tier includes software that communicates information about network availability and allocation.
- SDN controllers: Use information from the applications to determine how to route a data packet.
- Networking devices: These are the physical devices that receive information from the controllers on how to move the data.
While SDN addresses the application of Software-Defined Networking to networks in general, SD-WAN applies the concepts of SDN in Wide Area Networks. SD-WAN has two main features that make it unique, they are its ability to manage multiple connection types (LTE to MultiProtocol Label Switching (MPLS)) and segment, partition, and secure the traffic traversing the WAN. SD-WAN can be used by companies to link enterprise networks spanning large geographic areas. Businesses can connect remote offices and employees to securely deliver applications and information. ExternetWorks notes that before migrating to SD-WAN, it is important that a company critically examine its network infrastructure in the following ways:
- Assess access types
- Assess how the SD-WAN will integrate into your current network.
- Mapping out connectivity flows
- Choose a deployment model
- Keeping best practices and security policies up to date
- While planning your migration, consider executing a pilot test
- Site priority and applications for migration
- Monitor your network during the deployment process
- Efficient network monitoring
SD-WAN Architecture Types
There are three main SD-WAN architectures, they include:
- On-premise-only: This refers to configuring traffic through an SD-WAN box that cannot connect to a cloud gateway. It allows connection only between satellite offices and remote sites connected to the intranet.
- Cloud-based: This option allows connection to a virtual cloud gateway. This provides increased reliability and performance as compared to the on-premise-only architecture. It is best suited for companies that have cloud heavy applications.
- Cloud-enabled plus backbone: This is an architecture that offers a backbone connection to the nearest Point of Presence and thus, traffic transverses the service provider’s private network and fiber optic backbone.
SD-WAN Deployment Options
The three main deployment models are:
- Do It Yourself
- Managed SD-WAN
Just like all DIY models, it involves having full control over the deployment, configuration, and management of SD-WAN; it is suited for companies who have staff with the technical know-how to deploy and configure the SD-WAN network promptly. The managed SD-WAN model relies heavily on the provider of the service to provide technical personnel for the installation, configuration, and management of resources, thus allowing the businesses to focus mainly on business processes. However, this option comes with a higher cost than the previous model. In the hybrid model, the client and provider will co-manage the network; They will have free reign in generating application and security policies for whatever they intend to do with the network.
SD-WAN top applications
The applications used in managing SD-WAN are wide and varied, however, according to G2, some of the top SD-WAN applications in 2021 are:
- Cisco SD-WAN
- Cisco Meraki
- Cato Networks
- Aruba SD-WAN
- Oracle SD-WAN
- FortiGate SD-WAN
- Citrix SD-WAN
- Cisco Adaptive Security Virtual Appliance (ASAv)
SDN ushered in a new era in network management, and the adoption of SD-WAN would continue to improve as data grows and application complexity increases.