Networking Basics

A plain-language glossary of the networking terms you'll run into on these systems.

• Router — directs traffic between devices and out to the internet. In a vehicle, it's what gives the recorder its connection.
• Modem — (modulator/demodulator) translates network data into a signal that can travel over a cell, satellite, or wired network, and back again. Usually built into the router.
• Wi-Fi — the wireless network most routers provide. A Wi-Fi access point (AP) extends that wireless coverage over a larger area.
• Switch — like an access point but for wired connections; it adds more wired (LAN) ports to a router.
• Firewall — filters traffic going into or out of the network. It's built into the routers we use.
• LAN (Local Area Network) — the local network: a router plus the devices connected to it (wired or wireless).
• WAN (Wide Area Network) — the "outside" network the router connects to — e.g. the cellular carrier's network. The internet is millions of WANs connected together.
• WLAN — a wireless LAN (basically Wi-Fi). WWAN — a wireless WAN (like a cell network).
• Wi-Fi-as-WAN — using a nearby Wi-Fi signal as the router's internet source, instead of cellular.
• VPN (Virtual Private Network) — an encrypted "tunnel" across the internet so devices in different places can communicate securely, as if on the same local network.

Carriers used to just handle phone calls and texts — now they're also internet providers, which is how a bus gets online from anywhere.