Networks in Depth

The layers the first tour skipped and the extensions built on top — how bits reach the wire and the airwaves, how independent networks agree on routes, how the web reinvented its transport, and how private networks span the public internet.

5 articles

1. 1
   Networks & the Internet10 min

   Ethernet: How Machines Share a Wire

   The layer beneath IP: how a packet physically crosses a local network, why every device has a 48-bit MAC address, how a switch learns where each machine lives, and how ARP turns an IP into the MAC needed to actually deliver a frame.

2. 2
   Networks & the Internet10 min

   Wi-Fi: Networking Through the Air

   How Wi-Fi carries a link-layer over a shared radio medium, why it must avoid collisions instead of detecting them, and why the rated speed on the box is a ceiling everyone shares, not a promise to each device.

3. 3
   Networks & the Internet10 min

   BGP: How the Internet's Networks Agree on Routes

   The internet is a mesh of ~75,000 independently run networks. BGP is how they advertise reachable prefixes to each other and negotiate routes — driven by business policy, not shortest path, and held together by trust.

4. 4
   Networks & the Internet10 min

   HTTP/2 and HTTP/3: Reinventing the Web's Transport

   The verbs and headers of HTTP are the same as 1997, but the transport under them was re-engineered twice. HTTP/2 multiplexes many streams over one TCP connection; HTTP/3 throws out TCP entirely for QUIC over UDP to escape head-of-line blocking.

5. 5
   Networks & the Internet10 min

   VPNs and Tunneling

   A VPN builds an encrypted tunnel across the public internet by wrapping one network's packets inside another's — encapsulation — so a remote device can reach a private network as if plugged into the office wall.