Network Types — LAN, WAN, MAN & VPN
BeginnerNetworks are classified by geographic scope: PAN (personal), LAN (local), MAN (metro), WAN (wide area). VPN extends a private network securely over a public WAN.
Overview
Network classification by scope determines the technology, speed, and ownership model. A LAN (Local Area Network) connects devices within a building or campus — typically Ethernet or Wi-Fi, owned by one organisation. A WAN (Wide Area Network) spans cities, countries, or continents — the internet is the world's largest WAN. A MAN (Metropolitan Area Network) covers a city, often used by ISPs. A PAN (Personal Area Network) covers a few metres — Bluetooth, USB. For backend engineers, the key distinction is LAN vs WAN latency: intra-datacenter communication (LAN) is ~0.1ms; cross-region (WAN) is 50–200ms. VPNs create encrypted tunnels over public WANs to simulate being on a private LAN — used for remote access and connecting cloud VPCs to on-premise networks.
Network Types Comparison
Each network type has distinct characteristics in terms of reach, speed, latency, and ownership. These directly affect distributed system design — you treat intra-datacenter calls differently from cross-region calls.
// Network types at a glance:
// ┌────────┬─────────────────┬─────────┬──────────┬──────────────────────┐
// │ Type │ Scope │ Speed │ Latency │ Example │
// ├────────┼─────────────────┼─────────┼──────────┼──────────────────────┤
// │ PAN │ < 10 metres │ ~3 Mbps │ < 1ms │ Bluetooth, USB │
// │ LAN │ Building/Campus │ 1 Gbps+ │ < 1ms │ Office Wi-Fi │
// │ MAN │ City │ 100Mbps │ 1–10ms │ ISP city ring │
// │ WAN │ Global │ Varies │ 50–300ms │ Internet, MPLS links │
// └────────┴─────────────────┴─────────┴──────────┴──────────────────────┘
// In a microservices context:
// Service A → Service B (same datacenter, LAN): ~0.5ms
// Service A → Service B (different region, WAN): ~150ms
// This is why you keep chatty services co-located and use async
// messaging for cross-region communication.VPN — Virtual Private Network
A VPN creates an encrypted tunnel over a public network (WAN/internet) so remote clients or networks appear to be on the same private LAN. Site-to-site VPNs connect offices; client VPNs give remote employees access to internal resources.
// How a VPN tunnel works conceptually:
// Remote Developer → [Encrypted IPSec/TLS tunnel] → Corporate VPN Gateway → Internal LAN
// (public internet)
// AWS Site-to-Site VPN connects on-premise to AWS VPC:
// On-premise router ←→ AWS Virtual Private Gateway ←→ AWS VPC
// Types of VPN protocols:
// IPSec — standard enterprise VPN, operates at Layer 3
// OpenVPN — SSL/TLS based, flexible, port 1194 UDP
// WireGuard — modern, fast, minimal codebase, UDP-based
// Cloud VPN example (AWS SDK concept):
// CreateVpnConnectionRequest to link on-prem Customer Gateway
// with AWS Virtual Private Gateway over IPSec tunnelKey Points to Remember
- 1LAN: local network (building/campus), < 1ms latency, Ethernet/Wi-Fi.
- 2WAN: wide area network (internet), 50–300ms latency, leased lines or internet.
- 3MAN: metropolitan, city-scale, used by ISPs and large enterprises.
- 4VPN creates an encrypted Layer 3 tunnel over a public WAN.
- 5Intra-datacenter (LAN) latency ~0.1–1ms; cross-region (WAN) ~50–200ms — design systems accordingly.
- 6Cloud VPCs are private virtual LANs — inter-VPC traffic over a WAN requires VPC peering or VPN.
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