39 notes · CC BY 4.0
Network Engineering
The research behind course 004: packet flow, addressing, routing, services, security, labs and pedagogy.
Working notes from the research behind the course: mechanisms, tables, failure modes and sources. They are written for an engineer, not a beginner — the course is the beginner-facing version of the same material.
| Note | Length |
|---|---|
| Overview | |
| Network Engineering Network Engineering is the discipline of designing, implementing, operating, and troubleshooting communication networks. It provides the… | 858 words |
| Automation-Observability | |
| NetDevOps Fundamentals NetDevOps applies software practice to network operations: configurations in version control, changes through a pipeline, tests before deployment,… | 722 words |
| Packet Analysis with Wireshark Packet analysis is one of the most powerful skills for network troubleshooting. Wireshark lets you see exactly what's happening on the wire. | 643 words |
| Network Telemetry and Monitoring You cannot operate what you cannot see, and most networks are monitored by a graph nobody trusts. This note is about what to measure, how to… | 817 words |
| Cloud-Modern-Networking | |
| Cloud Networking Patterns The primitives are the same in every cloud — networks, subnets, routes, gateways, policy — but the defaults differ enough to cause real incidents… | 833 words |
| Overlays, SDN and VXLAN Modern data-centre and cloud networks separate what the network appears to be from how packets actually move. That separation is the… | 838 words |
| VPC Fundamentals Virtual Private Clouds (VPCs) are the foundation of cloud networking. They provide isolated, logically-defined networks in the cloud with full… | 795 words |
| Core-Protocols | |
| DNS, DHCP, and ICMP These essential network services handle name resolution, address assignment, and network diagnostics. | 693 words |
| HTTP Versions and QUIC HTTP/1.1, HTTP/2 and HTTP/3 solve the same problem — request and response over a network — with different assumptions about latency. Choosing… | 788 words |
| IP, TCP, and UDP These are the core transport and network layer protocols that make the internet work. | 682 words |
| Ports and Services A port is how one IP address hosts many conversations. It is also the first thing to check when something "cannot connect", and the thing people… | 975 words |
| TLS and HTTPS TLS is the layer that turns an untrusted network into a channel you can send a password through. It is also where a large share of "the API is… | 840 words |
| Foundations | |
| Addressing, Subnetting, and CIDR IP addressing is how devices identify and reach each other across networks. Subnetting allows you to divide networks efficiently. | 762 words |
| Ethernet, ARP, and Local Delivery Before a packet can be routed it has to survive one hop. This note is about that hop: framing, MAC addresses, ARP, and the very ordinary failures… | 836 words |
| Network Design and Topologies Topology is a decision about failure, not a picture. The shapes below exist because each one trades cost against blast radius, convergence time… | 830 words |
| Network Terminology Terms defined the way they are used in practice, ordered so that each one only depends on terms above it. This is the vocabulary spine for… | 1276 words |
| OSI and TCP/IP Models Understanding layered networking models is fundamental. They help you isolate problems and understand how data flows across networks. | 655 words |
| Packet Flow and Encapsulation One packet, followed from an application call to a wire and back. Everything else in networking is a detail of this journey, so it is the note to… | 846 words |
| Labs | |
| Home Lab Setup Networking is learned by breaking things you own. This note is the cheapest path from a laptop to a lab where you can cause a loop, blackhole a… | 1020 words |
| Subnetting Drills Subnetting is arithmetic, and arithmetic becomes fast with ten minutes a day. This note is the method, then the drills, then the answers. | 724 words |
| Troubleshooting Scenarios Ten failures, written the way they arrive: a symptom, no context, and a user waiting. Each one names the first question, the evidence that settles… | 999 words |
| Network-Services | |
| Firewalls, ACLs and Security Groups Every network has at least three policy layers, and they fail in different ways. Knowing which one dropped the packet is most of firewall… | 729 words |
| Load Balancing A load balancer is the component that turns one service into many without the client knowing. It is also where TLS terminates, where client IPs… | 792 words |
| NAT and PAT Network Address Translation rewrote the internet's addressing model as a workaround for IPv4 exhaustion. It is everywhere, it is invisible when it… | 941 words |
| NTP and Time Time is a security dependency disguised as a convenience. Certificates, tokens, logs, replication and authentication all compare clocks, and all… | 687 words |
| Pedagogy | |
| Course Blueprint (60 Minutes) The bridge between this vault and the interactive course. Ten modules, six minutes each, one running example, and a decision about what to leave… | 1614 words |
| Teaching Sequence and Analogies How to teach this material to an 18–55 year old with no networking background, in sixty minutes, without lying to them. This note is the course… | 1326 words |
| Where It Goes Wrong A taxonomy of the mistakes that actually happen in network engineering, sorted by where they originate. Every one of these is teachable in under… | 1234 words |
| Routing | |
| BGP and Internet Routing BGP is how the internet holds itself together: about 80,000 autonomous systems trading reachability information, mostly on trust. It is also the… | 851 words |
| OSPF Fundamentals OSPF is the interior routing protocol most enterprises actually run. It builds a shared map of the network and computes shortest paths from it,… | 785 words |
| Route Selection and Metrics Most routing incidents are not protocol failures. They are two routes disagreeing and the router choosing the one nobody expected. This note is… | 796 words |
| Routing Fundamentals Routing is the process of selecting paths for traffic to travel between different networks. Routers make forwarding decisions based on routing tables. | 797 words |
| Security | |
| DDoS and Availability Attacks Availability is a security property. An attacker does not need your data if they can make you unreachable — and the cheapest attacks rent for the… | 656 words |
| Network Security Fundamentals Network security is the discipline of deciding who may talk to what, and proving it. This note is the mental model: assets, trust boundaries, the… | 774 words |
| VPNs and Tunnels A tunnel wraps one packet inside another so it can cross a network it does not trust. Every tunnel is therefore two networks at once: the one the… | 786 words |
| Zero Trust and Segmentation Zero trust is not a product category. It is the decision to stop treating "inside the network" as a reason to trust, and to authorise every… | 720 words |
| Switching-LAN | |
| STP and Loop Prevention Ethernet has no TTL. A loop is not slow — it is a broadcast storm that saturates every link in seconds and takes the network down until someone… | 824 words |
| VLANs and Trunking VLANs (Virtual LANs) segment a single physical network into multiple logical networks, improving security, reducing broadcast domains, and… | 702 words |
| Wireless (802.11) Wi-Fi is a shared, lossy, half-duplex medium that behaves nothing like a cable. Most wireless "network problems" are capacity, airtime or… | 818 words |