LAN

A LAN is the network you own and operate. Every device connected to your home router — phones, laptops, smart TVs, printers — is on your LAN. Traffic between LAN devices never leaves your premises and is not metered by your ISP. Your router sits at the boundary between your LAN and the WAN (your ISP's network), performing NAT to let all LAN devices share a single public IP.

LAN vs WAN vs MAN

How a LAN works at Layer 2

Within a LAN, devices communicate using Ethernet frames addressed by MAC address, not IP address. An Ethernet switch sits at the centre of a wired LAN and learns which MAC addresses are reachable on which physical port by inspecting the source MAC of every incoming frame. This MAC address table lets the switch forward frames only to the port where the destination device lives — not to every port. This is fundamentally different from a hub, which broadcast every frame to every port regardless. Switches give each connected device a dedicated full-duplex link rather than a shared collision domain, which is why modern switched LANs deliver consistently high throughput.

IP addressing lives above this Layer 2 fabric. Your DHCP server (usually the router) assigns each device a private RFC 1918 address (10.x.x.x, 172.16–31.x.x, or 192.168.x.x). When device A wants to reach device B at its IP address, it first sends an ARP broadcast to resolve the IP to a MAC address, then the switch delivers subsequent unicast frames directly using its MAC table.

LAN topology: star via switch

Almost all modern LANs use a star topology: every device connects to a central switch via its own cable. This is why a single bad cable or NIC only affects one device rather than disrupting everyone. Home networks typically have a combined router/switch — the four LAN ports on the back form a small 4-port switch internally. Larger offices use dedicated managed switches with 24, 48, or more ports, sometimes stacked or linked via uplink ports for multi-floor deployments.

LAN addressing with private IPs

RFC 1918 reserves three address ranges exclusively for private (non-routable) use on LANs: 10.0.0.0/8 (16 million addresses), 172.16.0.0/12 (1 million addresses), and 192.168.0.0/16 (65,536 addresses). Home routers default to 192.168.0.x or 192.168.1.x with a /24 subnet mask, giving 254 usable host addresses. These addresses are never routed on the public internet — your router's NAT function translates them to your single public IP for outbound traffic.

VLANs: logical segmentation of a physical LAN

A VLAN (Virtual LAN) divides a single physical switch into multiple isolated logical networks. Devices in VLAN 10 cannot communicate directly with devices in VLAN 20 even though they share the same physical switch — the switch enforces the boundary. VLANs are widely used to isolate IoT devices, guest Wi-Fi, and corporate workstations on the same physical infrastructure. Traffic between VLANs must be routed through a Layer 3 device (a router or Layer 3 switch), giving you a firewall insertion point to control cross-segment traffic.

LAN speeds and cable standards

Wi-Fi as a LAN medium

Wi-Fi is a shared medium — all devices in the same frequency band and channel contend for airtime using CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance). A single client can potentially reach 1.2 Gbps on Wi-Fi 6 (802.11ax) with 80 MHz channels and 2-stream MIMO, but throughput drops as more devices compete for the channel. In contrast, a wired switch gives each device a dedicated full-duplex link with no contention. This is the fundamental reason wired LAN connections deliver lower latency and more consistent throughput than Wi-Fi, especially in congested environments like apartment buildings where many access points share the same RF spectrum.

LAN latency vs internet latency

A well-configured wired LAN has sub-millisecond device-to-device latency — typically 0.1–0.5 ms on a modern Gigabit switch. Wi-Fi adds 1–5 ms of wireless overhead. A round trip to a server across the internet involves multiple router hops, peering links, and geographic distance, typically adding 10–100 ms or more. This is why local LAN gaming, file transfers, and video calls between LAN devices feel instantaneous compared to internet-dependent equivalents. When you run a speed test, the measured latency is to the test server over the internet — not your LAN's internal latency.

Frequently Asked Questions

What is the difference between LAN and WAN?

A LAN is your local network — devices in your home or office that you control, connected at Layer 2 via switch. A WAN is the wide-area network beyond your router, including your ISP's infrastructure and the internet. Your router bridges the two, with a LAN side (private addresses, switch) and a WAN side (public IP, ISP link).

What speeds are typical on a home LAN?

Wired Gigabit Ethernet runs at 1 Gbps. Wi-Fi 6 delivers 400–900 Mbps in real-world conditions on 5 GHz with a good signal. Both are significantly faster than most home internet connections, making local file transfers much quicker than cloud-based alternatives.

Can devices on the same LAN transfer files faster than my internet speed?

Yes. LAN transfers stay within your local switch and never touch your internet connection. A wired Gigabit link copies files at up to ~112 MB/s — far faster than uploading to and downloading from an internet server on a typical broadband plan.