‹ All tracks

Computer Networks

How the internet works, layer by layer, with Python and simulators: delay, error detection, Ethernet and switches, IP addressing and subnetting, routing, TCP and UDP, reliable delivery, congestion control, DNS and HTTP.

• Online Python compiler
• Python code visualizer
• Networks exercises with solutions

1. 1

   How networks work: layers and packets

   Packets, packet switching, and the five layers of the internet, each adding its own header to your data.

2. 2

   Delay and throughput

   Where the time goes when a packet travels (transmission, propagation, queueing and processing delay) and why the slowest link sets the speed.

3. 3

   Detecting errors: parity, checksums and CRC

   Noise flips bits. Add a little extra information to every frame so the receiver can tell when something arrived damaged.

4. 4

   Ethernet, MAC addresses and switches

   How frames cross a local network: MAC addresses, switches that learn where everyone is, and ARP, which finds a MAC address from an IP address.

5. 5

   IP addresses

   IPv4 addresses in decimal and binary, the network and host parts, private addresses, NAT, and why IPv6 has 128 bits.

6. 6

   Subnetting Intermediate

   Work out a network's mask, network address, broadcast address and host range, and split a network into smaller subnets.

7. 7

   Routers and forwarding tables

   How a router chooses where to send each packet: forwarding tables, the longest matching prefix, and the default route.

8. 8

   Routing algorithms: link state and distance vector Intermediate

   How routers fill their tables: link-state routing with Dijkstra (OSPF), distance-vector routing with Bellman-Ford (RIP), and the count-to-infinity problem.

9. 9

   Ports, UDP and TCP

   The transport layer: ports and sockets, UDP's quick messages, and TCP's reliable connections with the three-way handshake and sequence numbers.

10. 10

    Reliable delivery: Go-Back-N and Selective Repeat Advanced

    Sequence numbers, ACKs and timeouts make delivery reliable; sliding windows make it fast. Compare how Go-Back-N and Selective Repeat recover from a loss.

11. 11

    TCP congestion control Advanced

    How TCP senders share a busy network: the congestion window, slow start, additive increase and multiplicative decrease, and how Tahoe and Reno react to a loss.

12. 12

    DNS and HTTP: the application layer

    How a name like example.com becomes an address, and what a browser and a web server actually say to each other.