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Engineering · Chapter 35 · English

Chapter 35 — Design studio II

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Chapter 35 — Design studio II

Lesson map

Lesson 35 published. Map, example, EX103.

flowchart TD
  N0["Learning outcomes"]
  N1["35.1 Reviewing what was built"]
  N2["35.2 Gaps raised"]
  N3["35.3 Responses"]
  N4["35.4 Presenting to stakeholders"]
  N5["Synthesis"]
  N0 --> N1 --> N2 --> N3 --> N4 --> N5
  N5 --> EX["Worked example"]
  EX --> Q["Exercise EX103"]

Logical drawing

flowchart LR
  N0["Learning outcomes"]
  N1["35.1 Reviewing what was built"]
  N2["35.2 Gaps raised"]
  N3["35.3 Responses"]
  N4["35.4 Presenting to stakeholders"]
  N5["Synthesis"]
  N0 --> N1 --> N2 --> N3 --> N4 --> N5 --> Q["EX103"]

[Learning outcomes]
    |
    v
[35.1 Reviewing what was built]
    |
    v
[35.2 Gaps raised]
    |
    v
[35.3 Responses]
    |
    v
[35.4 Presenting to stakeholders]
    |
    v
[Synthesis]
    |
    v
[Worked example] --> [Exercise EX103]

Learning outcomes

You will (1) refine the design after implementation; (2) address remaining gaps; (3) present to council stakeholders.

35.1 Reviewing what was built

Halfway through implementation, Kofi runs a second design studio with the council engineers, Dr Vasquez and two peers. The first studio reviewed plans; this one reviews what was actually built. He presents the deployed zone model, the measured fall in reachable zone pairs, the unexpected denies found and fixed, and the host-level exceptions that accumulated during migration. Comparing the built system with the design shows where reality diverged from intention, and those divergences are where the most useful lessons lie, because each one is either a design flaw, an implementation shortcut or a need nobody captured.

35.2 Gaps raised

Participants raise three gaps. First, staff at one office share a printer with guests in reception; the printer sits in the staff zone and is reachable from guest through a temporary rule added during migration. Second, guest wireless at two offices still uses an older captive portal on the same hardware as staff wireless, so a fault or misconfiguration could join them. Third, the management zone now contains a monitoring server that also needs internet access for updates, which blurs the boundary that made management the most tightly controlled zone. Each gap is small but undermines a requirement.

35.3 Responses

Kofi answers each gap with a specific change. A dedicated printer, reachable from guest only on the printing service, replaces the shared one, and the temporary rule is removed. The older guest wireless hardware is replaced so guest and staff networks are separated in the way NIST SP 800-153 recommends for wireless networks. The monitoring server fetches updates through the staff web filter instead of receiving direct internet access, so the management zone keeps its rule of no outbound connections. Every response is costed, given an owner and scheduled, and the temporary rule is removed within a week.

35.4 Presenting to stakeholders

The studio ends with a twenty-minute presentation to council managers, who care about service and cost rather than rule syntax. Kofi shows three things: the fall in reachable zone pairs, the original guest malware scenario now blocked, and the remaining work with dates and owners. Managers ask mainly about disruption, and he reports two short interruptions across six migrations, both resolved within the agreed change window. Translating technical results into service terms keeps managers' support, which matters because the remaining work, such as replacing wireless hardware, needs their budget approval.

Worked example

The studio produces a list of nine actions, each with an owner and a date; seven are completed before the end of implementation.

Synthetic case. The studio and actions are synthetic.

Errors and limits

Temporary rules added during migration tend to become permanent unless each has an expiry and an owner.

Exercises

Synthesis

Reviewing the built system against the design catches drift while it is still cheap to fix.

Continue studying — chapter 35 of 50

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