WAN (Wide Area Network)
A WAN is a network that connects multiple local networks across large geographic areas using public or private communication links.
What is a WAN?
A Wide Area Network (WAN) is a network that spans large geographic distances, interconnecting multiple Local Area Networks (LANs) across cities, countries, or continents. WANs rely on carrier services and long-distance links to transport data between sites.
The internet itself is the largest example of a WAN.
Why WANs matter
WANs are essential because they:
- Connect branch offices and data centers
- Enable access to centralized applications and services
- Support cloud and hybrid architectures
- Allow secure remote access at scale
- Provide business continuity across locations
Without WANs, modern distributed organizations could not operate.
Common WAN technologies
WAN connectivity can be delivered using:
- MPLS (private carrier networks)
- Leased lines (dedicated circuits)
- Broadband internet (fiber, DSL, cable)
- Cellular (4G/5G)
- Satellite (remote locations)
- SD-WAN (software-defined WAN)
Organizations often combine multiple options for resilience.
WAN vs LAN vs MAN
| Network type | Scope |
|---|---|
| LAN | Building or campus |
| MAN | City or metropolitan area |
| WAN | Regional, national, global |
WANs operate at a much larger scale than local networks.
WAN and security
From a security perspective, WANs:
- Carry sensitive data across untrusted paths
- Require encryption (VPN, TLS)
- Depend on strong access controls
- Are common targets for interception and disruption
Secure WAN design is critical to protect data in transit.
WAN and cloud connectivity
WANs play a central role in cloud adoption:
- Connecting on-prem networks to cloud providers
- Enabling hybrid and multi-cloud designs
- Supporting SaaS access for distributed users
- Integrating gateways and secure access services
Modern WANs increasingly prioritize cloud-first traffic.
SD-WAN and modern WANs
Traditional WANs are evolving with SD-WAN:
- Centralized policy management
- Application-aware routing
- Improved performance over the internet
- Built-in security features
- Reduced reliance on expensive private circuits
SD-WAN simplifies large-scale WAN operations.
Performance considerations
WAN performance depends on:
- Latency and jitter
- Bandwidth and congestion
- Packet loss
- Routing efficiency
- Quality of Service (QoS)
Application performance is often constrained by WAN quality.
Common misconceptions
- "WAN is just the internet"
- "WANs are always slow"
- "Private WANs don't need encryption"
- "SD-WAN replaces all network security"