WAN vs LAN vs MAN: What's the Difference?

Quick Definition: WAN, LAN, and MAN are all networks that cover different geographical areas. A WAN spans a large geographic area, such as a state or country, while a LAN covers a smaller area, usually a single building or campus. A MAN connects an area larger than a LAN but smaller than a WAN, typically covering a large town or metropolitan area. MANs are generally considered outdated in all but the most rural locations. 

The internet can accurately be described as a network of networks, interconnected groups of computers talking to each other locally and globally. To make these networks easier to describe, we generally define them using one of three terms: LANs, WANs, and MANs. 

Each has its own unique purposes and characteristics to meet the needs of networks as small as your house and as large as, well, the entire internet. Today, we'll explore these three network types and how they keep all our packets moving.

What is a WAN (Wide Area Network)?

The definition of a WAN is fairly broad and flexible, but generally it is a network that spans a large geographic area, like a state or country. WANs facilitate long-distance communication across these areas, connecting computers regardless of distance or specific location. The internet is a WAN, covering the largest geographic area possible (the earth) and then some (even into space, aboard the ISS). 

Key Characteristics of WANs

• WANs transmit data over long distances.

• They typically use telecommunication circuits and infrastructure leased from a private entity (like your local ISP or tier 1 carrier that connects all the ISPs to each other).

• WANs connect LANs to each other, forming an interconnected network we call the internet.

• Data is transmitted between connected LANs using routers (layer 3).

• When we think of WANs, we think of public IP addresses, which are reserved blocks of addresses assigned to devices directly connected to the internet, typically a modem or router. 

• While they generally have slower data transfer speeds compared to LANs, the difference is shrinking as last-mile fiber and 1+ gigabit internet speeds become more prevalent, at least in urban and suburban areas. 

• As a public network, security is a concern for connectivity across a WAN, with encryption and virtual private networks (VPNs) being crucial to maintaining privacy

WAN Technologies and Applications

There are two key WAN technologies that enable such a wide-reaching, distributed network to exist and function: fiber optic cabling and routers.  Fiber optics enable high-bandwidth communication across very large distances, sometimes over 100 miles.

Fiber uses glass fibers to carry modulated light. Different types of fiber are better suited for different applications; learn more about single-mode and multi-mode fiber.

While fiber carries the data across WANs, routers handle moving the packets in and out of individual LANs onto the greater WAN, acting as LAN gateways. They also determine the most efficient way of getting that traffic from point to point, optimizing for the shortest paths. While you might have a small router in your home or office, ISPs operate very powerful routers at regional hubs to move traffic across the country.

The Evolution of WAN

Today's high-speed WANs are based on technologies that date back to the telegraph from the 1840s. These early communication systems look like dinosaurs compared to what we use today, but the basics are there: two-way communication of messages sent across distances by electrical signals.

The telegraph eventually became switched phone systems, where humans and later electromechanical switches completed a circuit between your phone and the phone you wanted to call. Digital replaced all the electromechanical systems, but the core idea is still there: connect point A to point B to move data. WANs are very similar, replacing voice calls over copper with digital data over fiber.

What is a LAN (Local Area Network)?

A LAN is a much smaller network than a WAN and is typically limited to a single building or small campus. LANs are used for local networking (hence the name); a LAN not connected to the internet can only facilitate connections to other devices on the LAN.

Core Aspects of LAN

• LANs are only for connecting devices within a small area, such as a single building, house, or campus.

• They operate on equipment owned by the residents or organization.

• Data is transmitted between devices using switches (layer 2) connected via copper ethernet cabling.

• LANs use private IP addresses in a range usually defined by the router and assigned to devices by DHCP.

• Most switches sold in the last decade or two operate at 1 Gbps, but some higher-end switches might have 2.5 or 10 Gbps ports.

• Security within a LAN is still important, but connected devices are generally controlled by building access, so privacy is less of a concern on the LAN level.

LAN Technologies and Applications

As mentioned, LAN technologies revolve around switches and ethernet. Switches are layer 2 devices, meaning they operate at the data link layer of the OSI model, where we are concerned with MAC addresses rather than IP addresses. Switches talk to devices via MAC addresses and cannot route, so they don't talk to any device outside of the LAN.

LAN in Today's World

LANs are everywhere. Every business, every home, everywhere there are devices communicating on a network, there is a LAN. Mastering skills like subnetting, NAT, and common protocols (IP, DHCP, TCP, etc.) are essential early in your career.

The best thing about learning LANs is that the knowledge is fairly evergreen. Nothing new has come around for a long time, just small improvements to existing things, like faster switches or IPv6. If you get the basics down (which a cert like the CompTIA Network+ will teach you), you will be equipped with knowledge that won't be out of date anytime soon.

What is a MAN (Metropolitan Area Network)?

A MAN is a network that spans a larger geographical area than a LAN but smaller than a WAN, typically covering a city or metropolitan area. MANs serve as intermediaries between LANs and WANs, providing connectivity for urban environments.

In the late 1990s and early 2000s, more and more LANs within a metro area needed high-speed interconnectivity. Imagine a large, spread-out college campus with each building having its own LAN, where all these LANs need to communicate with each other. These connected LANs depended on connections over slow WAN connections, and the bandwidth needs were outgrowing capacity. 

This was before fiber was widely available. Single-mode fiber was used for long-haul phone network trunks, so it was adopted to provide private data links to customers within cities. The pressure on the WAN was relieved, businesses and colleges got the high-speed data they needed to connect their LANs without the expense of running their own fiber between buildings, and the MAN was born.

Unique Features of MAN

• MANs offer higher data transfer rates and lower latency than older WAN connections built on phone networks.

• They are operated by ISPs to provide private connections within metros.

• Data is transmitted over fiber using ISP-operated layer 3 routing to bridge the LANs.

• MANs don't use public IPs, since the traffic is only routed within their private networks.

• Data speed is dependent on the ISP and how robust their infrastructure is within the metro.

• Since the connections are private and traffic between customers on the ISP's network is logically separated, security is not a concern.

MAN Applications

MANs find applications in various urban settings, including:

• Large college campuses

• Municipal and government facilities within large cities

• Technology-rich cities like Silicon Valley had MAN backbones in the early 2000s to relieve data congestion within the cities due to high bandwidth needs

MANs Today

With WAN connectivity over copper phone lines a thing of the past in all but the most rural parts of the US, MAN networks have been made redundant. High-speed WAN connections are sufficient for both internet connectivity and LAN interconnectivity in applications where a MAN was previously necessary to support bandwidth needs between interconnected LANs.

Evolution of WAN, LAN, and MAN Technologies

The evolution of WAN, LAN, and MAN technologies has been driven by the need for more bandwidth. In LANs, switches need to be pushed from 10 MB to 100, then 1 GB, and then the 10 GB we see today. Greater demand drove evolution to make greater bandwidth the norm.

For WANs, bandwidth needs were met by moving from copper technologies like dial-up, ISDN, and T1 to fiber optics. Fiber can move much more data over much greater distances, making it the evolved standard both for trunks between cities and regions and for last-mile connections to neighborhoods and even directly into homes and businesses. Again, the need pushed the evolution ahead.

For MANs, fiber WANs were, in a way, their downfall. The original problem of overloaded copper circuits that created MANs was solved more thoroughly by fiber WANs, eliminating the need for MANs to interconnect metro-wide organizations.

In conclusion, network admins should know the differences between WANs, LANs, and MANs, as they are fundamentally different in implementation, technologies, and meeting users' needs. These network types are the building blocks of your organization's internal networks and the whole internet, so knowing the differences is crucial to planning and building resilient and scalable networks.

Want to learn more about networking? Check out our Networking Fundamentals course with Keith Barker.