Field Guide · hardware

A router is a networking device that forwards data packets between separate networks, deciding which path each packet should take toward its destination.1

LAN · 192.168.1.0/24 host .10 host .20 router routing table internet / WAN other networks forwards by destination IP joins separate networks — a switch only moves traffic within one
A router straddles two networks — here a home LAN and the internet — and reads each packet's destination IP against a routing table to pick the next hop across the boundary. That is what sets it apart from a switch, which only forwards frames inside a single network.

Overview

A router reads the destination IP address on each packet and consults a routing table to choose the next hop, moving traffic between networks rather than within one — that distinguishes it from a switch, which forwards frames inside a single network. The familiar home “router” is really several devices in one box: a router, a switch, a wireless access point, and often a modem, bridging a home LAN to the internet and performing address translation (NAT).

Where it fits

A router is the gateway between a local network and the wider WAN. On a GopherTrunk network it lets a capture node, a storage server, and a viewing laptop reach each other and, where desired, the internet — while keeping the capture node addressable on the LAN.

Sources

  1. Router (computing) — Wikipedia, on the device that forwards packets between networks. ↩

See also