WAN & SD-WAN: What You Need to Know

You probably had experience with WAN without even realizing it. Did you know that the Internet itself is considered as such?

It’s no secret that the intricacies of network technology can be overwhelming. Understanding the nuances between WAN and its cousin SD-WAN comes with a range of challenges, from mere terminology to the specific needs that warrant their implementation.

In this article, we will explore both, including their use, components, and what they bring to the table.

What is WAN?

Wide Area Network or WAN is a telecommunications network that extends over a large geographic area for the primary purpose of computer networking. WANs are used to connect multiple smaller networks, such as local area networks (LANs) or metropolitan area networks (MANs).

Technically speaking, any network encompassing a broad geographic region qualifies as a WAN.

Its main components are:

• Routers and switches - The former direct data between different LANs and across the WAN, making sure data reaches its destination efficiently. Meanwhile, switches connect multiple devices within a LAN and facilitate the local network’s connection to the WAN via routers.
• Leased lines - These are private, dedicated communication paths established between two or more locations. They provide a constant, reserved bandwidth between sites, ensuring that the performance is reliable and consistent.
• Public networks - Infrastructure provided by telecommunications companies and Internet Service Providers (ISPs) that is accessible to the general public. WAN utilizes that infrastructure, together with VPNs in some cases to connect remote locations securely over the public Internet, thus reducing the need for costly private lines.

Benefits and disadvantages

With its ability to connect offices, data centers, and cloud applications in general, WAN is used in many environments and scenarios, especially when it comes to large companies.

Here are some of the reasons why organizations use it:

• Large coverage - Can connect multiple locations across cities, countries, or even continents, allowing businesses to operate on a global scale.
• Data sharing - WANs facilitate the transfer of large volumes of data between locations, supporting business processes and decision-making.
• Reliability - Dedicated WAN connections, such as leased lines, provide stable and reliable communication with guaranteed bandwidth and low latency.
• Access to centralized resources - Enables remote offices and employees to access centralized resources like databases, applications, and file servers.

On the other hand, it might not be for everyone due to:

• High costs - Setting up and maintaining a WAN can be expensive due to the total price tag of leased lines, hardware, and ongoing management.
• Complex setup - WANs require sophisticated setup and ongoing maintenance, often necessitating specialized knowledge and expertise.‍
• Security risks - Can be vulnerable to security threats if not properly managed, requiring robust security measures to protect data.

What is SD-WAN?

Short for Software-Defined Wide Area Network, SD-WAN is a WAN architecture that uses software to manage network connectivity, control, and services between data centers, remote branches, and cloud instances. In other words, SD-WAN is the intelligence layer that manages how traffic travels through the WAN. It decouples the network hardware from its control mechanism, allowing for more efficient and flexible management.

Since SD-WAN goes hand in hand with WAN, the two have quite a bit of similarities, though SD-WAN focuses on different aspects. It consists of:

• SD-WAN edge devices - Physical or virtual devices located at the edge of the network at each branch, data center, or cloud location. They manage the traffic between the local network and the WAN, applying policies to optimize routing, security, and performance.
• Centralized management - Centralized software platform(s) that provides a single interface for configuring, monitoring, and managing the entire SD-WAN.‍
• Multiple connectivity options and multi-cloud connectivity - Utilizes various types of connections, such as MPLS (Multiprotocol Label Switching), broadband, and LTE. In addition, SD-WAN seamlessly integrates with multiple cloud platforms, delivering secure and dependable access to cloud-based resources and enhancing overall network performance and flexibility.

Benefits and disadvantages

Being a newer technology of the two (the term popped up in 2014), SD-WAN is being used more and more in today’s cloud-focused world.

To give you an idea of why that’s the case, here are some of the advantages of SD-WAN:

• Cost-effective - Can reduce operational expenses by using lower-cost internet connections (such as broadband or LTE) alongside or instead of expensive MPLS circuits.
• Improved performance - Optimizes traffic and reduces latency by dynamically selecting the best path.
• Flexibility - Easily adds or removes branch locations, adjusts bandwidth, and implements new policies without significant changes to the infrastructure.
• Enhanced security - Includes built-in security features like encryption, segmentation firewalls, and secure web gateways, leading to improved overall security posture.
• Redundancy - Multiple connections (broadband, LTE, etc.) provide redundancy, improving network resilience and uptime as a result.

Just like with every other tech, there are some disadvantages:

• Quality of Service (QoS) challenges - Guaranteeing end-to-end QoS tends to be difficult, especially when using multiple internet connections.
• Vendor lock-in - Choosing a specific SD-WAN vendor can lead to dependency on that vendor's technology and services.
• Relatively new technology - SD-WAN market is still evolving and has yet to be fully adopted, and some solutions might lack the stability of established technologies.

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