Networking

Part of Phase 5: Rebuilding Technology

Networking itself is the overview: a basic serial link holds to 100 meters at 9,600 baud, but drop to 300 baud and the same wire stretches past 500 meters before signal quality gives out.

Communication Need, Networking, Resource Sharing, and Shared Resources cover why a network exists at all. Networking solves three pressures — resource scarcity, information asymmetry, and the plain need to coordinate work across isolated computers — and the original economic case is concrete: sharing one fast printer among twenty people costs less than giving each of them a slower one. A storage quota set at 20 GB against a typical 5 GB of real usage catches a runaway process without constraining anyone doing normal work.

Network Topologies, Bus Topology, Star Topology, Topology Comparison, and Network Types cover how machines physically connect. A full mesh network’s link count explodes fast — five nodes need 10 links, ten nodes need 45 — which is why mesh stays rare past a handful of devices, and a flat bus network turns unreliable past roughly 30 devices while a well-designed hierarchical star scales to thousands. A point-to-point wireless link at 2.4 or 5 GHz can span 10-50 km between towers, covering a city’s distance without laying a meter of cable.

Twisted Pair Wiring, Physical Connections, Connectors, Network Hardware, Network Interface, and Hub Construction cover the physical layer. Cat5e tops out at 1 Gbps over 100 meters, Cat6 pushes 10 Gbps to about 55 meters, and Cat6a holds 10 Gbps the full 100 meters — the real difference buyers pay for. An RJ-45 plug packs 8 contacts into one jack, while a single-mode fiber connector has to align a core only 8-10 micrometers wide to avoid signal loss, and a minimal 4-port Ethernet hub needs just a 10 MHz crystal to repeat every incoming signal to all other ports.

Start-Stop Bit Framing and Serial Connections cover the simplest links. Start-stop framing adds 2 overhead bits to every 8 data bits, capping efficiency at 80% — the price of finding message boundaries with no shared clock — and RS-232, introduced in 1969, tops out around 15 meters of cable run.

Ethernet Basics, CSMA/CD, Collision Handling, Frame Format, and Error Detection cover the dominant wired standard. Ethernet, developed at Xerox PARC in the early 1970s and standardized as IEEE 802.3, grew from a 10 Mbps bus network into today’s multi-gigabit switched one, though real CSMA/CD networks run at no more than 30-40% of theoretical capacity. Detecting a collision triggers a 32-bit jam pattern and backoff, within about a 1.6 microsecond detection window on a 185-meter coax segment, and Ethernet’s own CRC-32 catches every single-bit error, every burst under 32 bits, and over 99.9999% of longer bursts.

Network Addressing, Routing Basics, and Network Fundamentals cover getting a packet to the right place. Port numbers let one IP address run many services at once — web traffic defaults to port 80 or 443, DNS to port 53 — and a /24 subnet provides 254 usable addresses against just 2 for a /30, the minimum for a link between two routers. Pushing one 1,500-byte packet onto a 100 Mbps link takes about 120 microseconds, and multiplying that by round-trip time is where the bandwidth-delay product comes from.

Packet Structure, Packet Switching, Protocols, File Transfer, Messaging, and Acknowledgments cover what actually travels the network. Packet switching slices data into pieces no larger than the network’s MTU, typically 1,500 bytes, so many conversations interleave on one shared link, and DNS exists because turning a domain name into an address by hand doesn’t scale. A satellite link’s 500 ms round trip is why stop-and-wait with 1 KB packets at 1 Mbps manages only about 2% efficiency, which is exactly what sliding windows exist to fix, and Metcalfe’s law shows up directly in messaging — a 10-person network supports 45 unique communication pairs, a 100-person network 4,950.

Networking Fundamentals through Intrusion Detection cover what a settlement can actually build: a local network from salvaged switches, twisted pair and a few machines, with file sharing, mail and a web server inside the settlement. The global internet is not recoverable, because it depended on undersea cable, carrier routers and the institutions that issued addresses and certificates, so these articles size everything to a settlement and its neighbours. A /24 split into four /26 subnets leaves 62 usable hosts in each, four consecutive /24 blocks starting at 10.1.0.0 combine into one /22 of 1,024 addresses, and a 250 GB first copy takes about 5.6 hours at 100 Mbps but about 23 days at 1 Mbps.

Why Networks Exist

The economic and practical case for connecting isolated machines at all.

Topologies

The shapes a network can take, and why most settle on a hierarchical star.

Physical Layer and Hardware

The cable, the connector, and the box that repeats a signal to every other port.

Serial Links

The simplest connection there is: one wire, one byte at a time.

Ethernet

The dominant wired standard, its access method, and the error it catches on every frame.

Addressing and Routing

Getting a packet to the right machine, and the subnet math that makes it possible.

Packets and Protocols

What actually travels the network, and the rules that keep it arriving intact.

Building the Network: Orientation and Layers

What a salvaged network can and cannot be, and the layered model that locates a fault.

Building the Network: Cable, Fibre, Radio and Switches

Making, testing and laying the physical links, and joining them with switches.

Building the Network: IP Addressing

Numbering a settlement, splitting blocks into subnets with checked arithmetic, and handing addresses out.

Building the Network: Routing

Choosing static or dynamic routes, how each family works, and why the border protocol of the old internet does not return.

Building the Network: Core Protocols and Names

The transports, the name service and the web protocol a settlement runs.

Building the Network: Servers

Planning and running the services a settlement uses every day.

Building the Network: Security

Defending a settlement network against the threats that can reach it, and treating trust as a problem of agreement.

Explorer