About The Codex Lab

Who’s behind The Codex Lab

I’m JT. I love both building technology and helping people understand it. As a courseware developer with a software engineering and technical writing background, I built these labs to make networking concepts easier to see, explore, and learn by doing. I’m passionate about the intersection of engineering and education, and I’d love to connect with others who enjoy building and teaching technology. Take a look around, try the labs, and don’t hesitate to reach out.

Who it’s for

• Engineers testing an intuition before a change
• Students and candidates learning how a protocol actually behaves
• Instructors who want a live diagram instead of a static slide

What’s inside

Spanning Tree Explorer

Drag priorities and path costs on a five-switch topology; watch root election, blocked ports, RSTP reconvergence, and traffic traces — then run the same cabling loop-free with every link forwarding.

OSPF Explorer Pro

Adjacencies and DR election, LSA types 1–7, multi-area design with stub and NSSA, cost-based SPF route selection, and OSPF/BGP redistribution across five live topologies.

Subnetting Lab

Explore an IPv4 address bit by bit, split a block into VLSM subnets, and drill practice questions until the math is automatic.

Number Bases Explorer

Convert between decimal, hex, binary, and octal with 32-bit grids, plus worked MAC, IPv4, IPv6, and port examples.

RF Math Explorer

dBm/mW conversion, gain and loss chains, EIRP, path loss, received power, fade margin, Fresnel clearance with an outdoor point-to-point diagram, dish gain, and a link-quality estimator.

MU-MIMO Explorer

A multi-user wireless demo for sounding, compressed beamforming feedback, client grouping, spatial-stream allocation, single-user versus grouped airtime, and practice questions.

802.1X Explorer

Wireless authentication end to end: WPA2-PSK and WPA3-SAE, Enhanced Open, identity PSK, MAC auth bypass, and 802.1X with EAP-TLS, PEAP, TTLS, and TEAP — plus a config builder, fault injection, and practice questions.

Glossary

Plain-language definitions for every term the labs use, searchable and filterable, each linked to the lab where it appears.

How it’s built

Visual over memorization

Move the controls and watch the protocol respond, instead of memorizing an output.

Browser-only

No accounts and no paid services behind the labs — the math runs on your device.

Print-friendly

Every page prints cleanly on light paper, so a lab can become a handout.

Dark and light

A field-notebook dark theme by default, with a warm light mode on demand.

What you can do right now

Open any lab from the homepage explorer, or start with the glossary if a term is new. No sign-up, no setup — just the protocol, made visible.