MPLS and SD-WAN

In short: MPLS and SD-WAN connect a company’s sites. MPLS is a private network run by a provider with guaranteed quality, SD-WAN steers several inexpensive lines by software.

In more detail: Branches used to be connected via leased MPLS lines. Today SD-WAN replaces or complements them with ordinary internet access.

In Depth

• MPLS: Packets receive short labels. Routers forward by label instead of IP address, which is fast and permits fixed paths and service classes. Reliable but expensive and tied to one provider.
• SD-WAN (“software-defined WAN”): A central controller manages devices at the sites. It bundles several lines (fibre, DSL, 5G), measures quality and steers applications as needed, such as video conferences onto the best line.
• Encryption: Traffic over the internet is protected by tunnels (IPsec or WireGuard).
• Advantages of SD-WAN: Lower cost, quick rollout, a direct route to the cloud instead of a detour via headquarters.
• Disadvantages: The internet offers no quality guarantee. Good monitoring is needed.
• See also: QoS, VPN.

See also: BGP and routing on the internet