WANs

A wide area network (WAN) is a telecommunications network that covers a broad geographic area, connecting multiple smaller networks such as local area networks (LANs) and metro networks. WANs enable offices, data centers, and remote sites to communicate and share resources over long distances, using private networks, public networks, or a combination.

WANs are typically built with carrier-provided communications links and network equipment at each site. Common technologies include leased lines, MPLS, and carrier Ethernet, as well as VPNs over the public Internet. More recently, software-defined WAN (SD-WAN) technologies manage and orchestrate WAN connections, providing centralized control, path selection, and policy enforcement across heterogeneous links.

WAN architectures vary: point-to-point links between sites, hub-and-spoke models with a central data center, full-mesh interconnections, or hybrid designs that mix several approaches. Routing and sometimes switching equipment, along with firewalls and WAN optimizers, are deployed at branch offices and data centers.

Performance and reliability in WANs are affected by latency, jitter, and bandwidth, and are managed with quality of service (QoS), caching, compression, and WAN optimization. Security concerns include encryption (such as IPsec VPNs), access control, and segmentation. Service level agreements govern availability and performance, as WANs underpin enterprise networking, cloud connectivity, and disaster recovery.