Chapter 11 — Networks and protocols
Lesson map
Lesson 11 published. Map, example, EX031.
flowchart TD
N0["Learning outcomes"]
N1["11.1 Paths through the network"]
N2["11.2 Protocols and integrity"]
N3["11.3 Availability and buffering"]
N4["11.4 Documenting flows"]
N0 --> N1 --> N2 --> N3 --> N4
N4 --> EX["Worked example"]
EX --> Q["Exercise EX031"]
Logical drawing
flowchart LR
N0["Learning outcomes"]
N1["11.1 Paths through the network"]
N2["11.2 Protocols and integrity"]
N3["11.3 Availability and buffering"]
N4["11.4 Documenting flows"]
N0 --> N1 --> N2 --> N3 --> N4 --> Q["EX031"]
[Learning outcomes]
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v
[11.1 Paths through the network]
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v
[11.2 Protocols and integrity]
|
v
[11.3 Availability and buffering]
|
v
[11.4 Documenting flows]
|
v
[Worked example] --> [Exercise EX031]
Learning outcomes
You will (1) trace how meter and sensor data cross networks; (2) assess protocol choices for integrity and availability; (3) document network data flows for governance.
11.1 Paths through the network
Meter readings travel by radio to collectors on street poles, then over a mobile network to a vendor's head-end platform, then over the internet to Tidewater's data centre. Sensor readings follow a separate path over a private industrial network to the control system. Kofi draws both paths and labels each hop with the protocol, the operator and whether data are encrypted. He finds that the governance owner changes at each boundary, which explains why nobody could answer questions about end-to-end delays or losses.
11.2 Protocols and integrity
The meter path uses an encrypted, authenticated protocol from collector to head-end, so readings are protected against tampering in transit. The industrial network uses an older protocol without authentication, which relies on the network being isolated. Kofi notes that this does not make sensor data wrong, but it means Tidewater cannot prove from the protocol alone that a reading came from a genuine sensor. He records the gap and recommends monitoring for unexpected devices on the industrial network. An alert now fires for unknown devices.
11.3 Availability and buffering
Network outages delay data. Collectors buffer readings for up to two days; the mobile network occasionally drops for hours. Kofi measures, on synthetic logs, how often readings arrive more than six hours late and finds that most late arrivals cluster around storms. He argues that data consumers such as billing must be told how late data can legitimately arrive, so that they do not treat late readings as missing or estimate bills unnecessarily before the real readings land. The billing team now waits forty-eight hours.
11.4 Documenting flows
Kofi produces a network data flow document with each hop, owner, protocol, encryption, buffering and typical latency. The document is reviewed by the network team and the data governance lead. It becomes the reference when Tidewater negotiates a service level with the metering vendor. Prof. Varga notes that a governance owner cannot be accountable for data they cannot see, and that documenting flows across organisational boundaries is how accountability becomes possible in practice. The vendor service level now includes a maximum delay for buffered readings after an outage.
Worked example
Kofi traces meter and sensor paths, finds an unauthenticated industrial protocol, measures storm-related delays and documents every hop with owners and latencies.
Synthetic case. Networks are synthetic.
Errors and limits
Flow documents age quickly; review them after network changes.
Exercises
- EX031 — Owner changes. Why could nobody answer end-to-end questions? Rubric: 3 = the governance owner changes at each boundary;; 2 = mentions boundaries;; 1 = vague;; 0 = none.
- EX032 — Industrial gap. What gap did Kofi find on the industrial network? Rubric: 3 = no protocol authentication;; 2 = partly correct;; 1 = vague;; 0 = none.
- EX033 — Late data. When do late arrivals cluster? Rubric: 3 = around storms;; 2 = partly correct;; 1 = vague;; 0 = none.
Continue studying — lesson 11 (chapter 11 of 50)
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