LAN, WAN, MAN — networks by scale

Networks are categorized by how big an area they cover. The boundaries are fuzzy, but the categories matter because they imply different technologies, ownership models, and design constraints.

| Scope | Acronym | Typical size | Owns the medium? | Examples | |---|---|---|---|---| | Personal | PAN | A few meters | You | Bluetooth between phone and headphones | | Local | LAN | One building or campus | You | Office Ethernet, home Wi-Fi | | Metropolitan | MAN | A city or metro | Sometimes you, sometimes a service provider | A university with multiple sites across a city, a city-wide municipal fiber | | Wide-area | WAN | Country to global | Almost never you | MPLS WAN between offices, leased lines, the public internet |

Why the distinction matters

LANs are usually fast, cheap, and entirely under your control. You buy switches, run cables, deal with your own broadcast storms. Bandwidth is rarely the bottleneck — 1 Gbps to the desk is the floor, 10/25/40/100 Gbps backbones are routine.

WANs are usually slow, expensive, and partly under someone else's control. You pay a carrier for an end-to-end "circuit." That circuit might be a real fiber, or a virtual path through the carrier's MPLS core. Bandwidth is precious. Latency is measurable. You design around it.

MANs sit in between and the lines blur. Many enterprise "WANs" are technically MANs (a few sites within the same city, connected by leased fiber). The CCNA exam doesn't dwell on the distinction; the terms exist mainly so we share vocabulary.

Operator-grade examples (relevant to this course)

The hardware you'll be working with maps to these categories:

• Cisco IE4000 — industrial LAN switch (substations, factory floors). Often Ring or daisy-chain topology, ruggedized for temperature and vibration.
• Nokia 7705 SAR-8 v2 — cell-site / aggregation router. Lives at the boundary between LAN-ish access (one site) and MPLS WAN (back to the core).
• Nokia 7750 SR-a8 — service router. Pure WAN/operator gear, pushes MPLS labels, runs BGP, terminates VPN services.
• Cisco ASR (1000/9000) — same role as the 7750 in Cisco shops.
• Ciena 6500 / Waveserver — optical transport. The DWDM gear that carries everyone else's WAN traffic over long-distance fiber.

You'll meet each in detail in Track E.

What to remember

• Categories: PAN, LAN, MAN, WAN — by scale.
• LAN = you own it. WAN = someone else owns it and bills you monthly.
• The category implies a different mindset: LAN you optimise for speed; WAN you optimise for cost-per-bit and reliability.