2.1 Computer Networking
Computer networking carries every byte your enterprise produces. The OSI and TCP/IP models, IP addressing, and the LAN/WAN distinction are the foundation everything else builds on.
2.1 Fundamentals of Computer Networking
OSI vs TCP/IP layers
TCP vs UDP - choose by reliability vs speed
| Protocol | Reliability | Order | Typical use |
|---|---|---|---|
| TCP | reliable + retry | ordered | HTTP, SSH, SMTP, databases |
| UDP | best effort | unordered | DNS, VoIP, gaming, video |
| QUIC | reliable + retry | multiplexed | HTTP/3 default |
Bandwidth, latency, and throughput
| Metric | Definition |
|---|---|
| Bandwidth | bits per second the link can carry |
| Latency | one-way time for a bit to reach the destination |
| Throughput | bits per second your app actually achieves |
| Jitter | variance in latency (matters for voice and video) |
A 100 Mbps link with 100 ms latency feels worse than a 50 Mbps link with 10 ms latency for interactive work.
Quick math - bandwidth-delay product
bandwidth-delay = bandwidth x round-trip-time
A 100 Mbps link with 60 ms RTT carries about 750 kB of in-flight data. Tuning TCP window size below this wastes capacity.
Where this connects to EA
The Technology Architecture layer documents which apps use which links, the redundancy of each link, and the SLAs of each ISP. Without it, capacity planning is guesswork.
Mentor’s tip: TCP/IP for operation, OSI for vocabulary. Choose TCP or UDP by reliability needs. Bandwidth and latency are not interchangeable - the bandwidth-delay product tells you when to tune.
Discussion
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