SD-WAN or overlay based WAN

SD-WAN technology is one of the most talked-about topics in the networking world today. But what is SD-WAN, and why should you care?

Software-Defined WAN (SD-WAN) is a type of wide area network (WAN) technology that allows for more flexibility and scalability. SD-WAN works with software to control the routing of traffic across a network. This means that companies can use any type of Internet connection, including broadband, cable or even mobile data, to connect their sites.

SD- WAN also makes it easy to add new connections or sites to a network. With traditional WANs, adding a new site can be a complex and expensive process. With SD-WAN, however, companies can simply add a new router and configure it remotely through the software. This makes expanding a network much easier and less expensive.

SD-WAN separates control plane traffic and data plane traffic. Data plane traffic is held between edge devices installed at the site or in the cloud, and a direct tunnel is established, while routing decisions are made by the controller managing the control plane. In most implementations, IPSec tunnels are established between devices using any transport such as MPLS, Internet (DIA, BIA) or LTE/5G.

Network management is highly streamlined in SD-WAN solutions. Application traffic can be dynamically routed based on current network conditions, policies, priority hierarchies, and/or cost considerations, while link bandwidth is aggregated to ensure cost-effective utilization and policy-driven performance.

SD-WAN is not an RFC, but a technology, and all vendors offer proprietary hardware and software that is implemented in different ways.

Gartner examines all vendors for their different functions or the problems they solve for customers. It also talks to vendors’ customers to rate them on a scale of easy to hard.

What are some characteristics of SD-WAN?

• • SD- WAN is a flexible overlay architecture that enables enterprises to take control of their applications and WAN infrastructure to better meet enterprise network needs
  • Defines, provides visibility and high-level control of global network policies
  • Enables application visibility with Real-time analytics
  • Improve application performance for end users – create policies according to how traffic needs to be handled for specific applications. Fine-tune according to business requirements
  • Load balancing and better availability of traffic on an active/active basis between the two connections
  • Better use of DIA and BIA based on criticality of traffic and provides fallback options as Failover and network resilience with sub-second failover offered by most vendors
  • Secure – integrated stateful firewall and policies are centrally managed
  • Cost savings through better utilization of traffic when combined with Internet or MPLS circuits
  • WAN optimization: available from few vendors to further improve application performance – for example, through compression and data deduplication and TCP optimization – while reducing associated bandwidth costs.
  • A cloud-on-ramp via a SD-WAN provides a direct, secure and highly available connection between branch offices and IaaS/PaaS clouds or between different geographic locations. A virtual SD-WAN appliance in the cloud and a SD-WAN appliance in the branch office can be used to create a SD-WAN overlay tunnel. 

 I have mostly worked on HP SilverPeak, Cisco Viptela, Fortinet SD-WAN, Meraki, VeloCloud and Versa SD-WAN. Few vendors offers SASE builtn as well as integration with Zscaler and Prisma cloud.