Network Stories
One story, one network feature
The Network Buddies run into the same troubles real networks face, then discover the clever fixes engineers came up with. The 22 stories go from easy to harder, so reading them in order works best. Each story lists what to read first.
Part 1: Inside One LAN (Layer 2)
- Beginner ✓ Read 1. Octo's First Day: How a Switch Delivers Three computers want to share photos with each other. Can we just run a cable between every pair?
- Beginner ✓ Read 2. Octo's Predecessor: Hubs and Collisions What happens if everyone talks at the same time?
- Beginner ✓ Read 3. Who Is 192.168.1.11? ARP (Address Resolution Protocol) If you only know someone's IP Address, how do you find their MAC Address?
- Beginner ✓ Read 4. The Invisible Cable: Wi-Fi and Access Points Your phone has no network cable plugged in. So how does its data get into the LAN?
- Intermediate ✓ Read 5. One House, Two Zones: VLAN (Virtual LAN) Why can't the guest Wi-Fi see the computers in your home?
- Intermediate ✓ Read 6. One Cable, Many Zones: Trunks and 802.1Q Tags There's only one cable between two Switches. How can it carry data for two VLANs at once?
- Intermediate ✓ Read 7. Octo's Broadcast Storm: Spanning Tree Protocol Adding an extra cable should make the network more reliable. So why did the whole LAN grind to a halt?
- Intermediate ✓ Read 8. Two Cables Pulling Together: Link Aggregation STP switched off the spare cable. Is there a way to use both cables at once?
Part 2: Leaving the LAN (Layer 3)
- Beginner ✓ Read 9. Out the Front Door: Router and Default Gateway Octo can't deliver to other networks. So who should the letter be handed to?
- Intermediate ✓ Read 10. A Bridge Between Zones: Inter-VLAN Routing The family zone and the guest zone are kept apart. But sometimes they need to talk. How?
- Intermediate ✓ Read 11. The Art of Cutting Cake: Subnetting There's only one block of addresses, but it has to be shared by three networks. How do you cut it just right?
- Intermediate ✓ Read 12. Rue's Map: Routing Tables and Static Routes How does Rue know the "next stop" for every letter?
- Intermediate ✓ Read 13. The Routers Swap Notes: Dynamic Routing and OSPF A city has a hundred Routers. Who keeps every single map up to date?
- Intermediate ✓ Read 14. The Building Office: NAT and Port Forwarding A whole family shares one Public IP. So how does each reply find the right person?
Part 3: Transport and Services
- Intermediate ✓ Read 15. Did Pip Arrive Safely? TCP Sequence Numbers and ACKs A photo is cut into lots of packets. What happens if one goes missing?
- Beginner ✓ Read 16. The Network Doctor: ICMP, Ping and Traceroute When you can't get online, how do you find out which stop the problem is at?
- Intermediate ✓ Read 17. The Sealed Letter: HTTPS and TLS What exactly does the padlock next to the web address lock up?
Part 4: Security and Reliability
- Intermediate ✓ Read 18. The Secret Tunnel: VPN (Virtual Private Network) When you're online in a coffee shop, how can you safely connect back to your home or office network?
- Intermediate ✓ Read 19. The Guard at the Door: Firewalls and ACLs Every packet wants to come in. How does Pango decide which ones to let through and which ones to stop?
- Intermediate ✓ Read 20. No Fear of Crowds: Load Balancers and High Availability When millions of people open the same website at the same time, why doesn't the server collapse?
Part 5: One-to-Many Delivery
- Beginner ✓ Read 21. Unicast, Broadcast, Multicast & Anycast Two TVs want to watch the same live match. Should we send two copies, or one copy to the whole house?
- Intermediate ✓ Read 22. IGMP Snooping The TV in the living room is showing a live stream. So why is the phone in the study so slow online?