AP Networking 2.3: Upgrade a SOHO Network

Upgrading a network is three decisions made in order: which endpoint device fits the user's need, which transmission medium (copper, fiber, or wireless) carries its traffic, and whether it gets a static or dynamic IP address. The test for every choice: it must satisfy ALL the stated constraints, not most of them.

This is Topic 2.3 of AP Networking Unit 2. You fixed the computer lab in 2.1 and documented it in 2.2, and the reward is a budget. Every request that lands on the tech team's desk is now a constraint-matching exercise: bandwidth, distance, interference, mobility, and money all get a vote.

• The three upgrade decisions
• Choosing endpoint devices
• Copper vs fiber vs wireless
• Wired or wireless: decide by constraint
• Static vs dynamic IP addressing
• Writing the upgrade plan
• Worked examples
• Practice: Upgrade Architect
• Using AI safely
• Key terms
• Frequently asked questions

The three upgrade decisions

Every upgrade request reduces to the same three questions, asked in order. First, which device: desktop, laptop, tablet or phone, or a shared peripheral. Second, which link: copper Ethernet, fiber, or wireless. Third, which address: static, findable forever, or dynamic from DHCP.

The exam skill is elimination: cross off every option a single constraint kills, and what survives is the answer.

Choosing endpoint devices

Match the device class to the user's need, then check cost, performance, and portability against what was asked for. Missing one stated need fails the user; exceeding it wastes budget another request could have used.

Device	Strengths	Costs you accept	Pick it when
Desktop	Best sustained performance, upgradeable parts	Stays at one desk	Heavy fixed work: editing, rendering, serving files
Laptop	Real performance that travels	Lower ceiling, battery, higher cost per unit of speed	Performance needed in more than one place
Tablet / phone	Mobility-first: light, instant-on, all-day battery	Weakest for sustained heavy work	Movement is the job: scanning, checklists, lookups
Printer / scanner / smart device	One device serves everyone	Needs a reliable link and a findable address	The need is shared, not personal

How the device connects is part of the choice. A wired NIC gives a dedicated, reliable link but tethers the machine to a jack; wireless frees it to move and puts it on shared airtime. A desktop on Wi-Fi is a design smell: it gave up the dedicated link and got nothing back.

Copper vs fiber vs wireless

Every transmission medium is a bundle of six tradeoffs: signal type, speed, distance, interference, mobility, and cost. No medium wins all six; the scenario's constraints decide.

	Copper twisted pair	Fiber optic	Wireless (Wi-Fi)
Signal	Electrical	Light	Radio waves
Typical speed	1 Gbps routine (Cat5e/Cat6)	Fastest: 10 Gbps and up	Drops as devices share airtime
Distance	About 100 m per run	Kilometers	Tens of meters, less through walls
Interference	Immune to Wi-Fi congestion	Immune entirely	Walls, distance, and neighbors cut throughput
Mobility	None: tethered	None: tethered	Full: the whole point
Cost	Cheapest	Highest to buy and install	Low once the AP exists

Fiber is the fastest medium, covers the longest distances, and costs the most, which tells you where it belongs: backbones, building-to-building runs, ISP lines. Fiber prices for a 9 m desktop drop buy speed copper already delivers.

Wired or wireless: decide by constraint

Wireless is not the modern replacement for cables. Every device on an access point shares the same airtime, so 30 active wireless devices split one radio's capacity while every wired desktop keeps a dedicated 1 Gbps lane. That is why lab Wi-Fi crawls at 2 pm while the wired machines stay quick.

The decision rule is short. Does the device move as part of its job? Wireless, no debate: mobility is the one constraint only wireless satisfies. Does it stay put? Wire it.

Static vs dynamic IP addressing

From 2.2 you know the network assigns the IP address. This topic decides HOW, for each device.

	Static	Dynamic (DHCP)
Who sets it	A person, once, by hand	The DHCP server, automatically
Does it change?	Never	Can change at lease renewal
Conflict risk	Real: hand-typed duplicates collide	None: the server tracks the pool
Scales?	Poorly: every address is bookkeeping	Yes: devices join and leave freely
Use it for	Devices others must find: printer, file server, camera, router	Everything else: laptops, tablets, phones, desktops

The static list is short and specific: a device earns a fixed address only when other devices are configured to find it there. Print queues point at the printer's address, clients mount the file server by address, and you browse to the router's address to manage it. Drift breaks all of that. Everything else belongs on DHCP.

DHCP reservations: both at once

A DHCP reservation ties one MAC address to one IP address on the DHCP server: the printer asks for an address like any client and always receives the same one. Nothing is typed into the device by hand, and the MAC comes straight out of the documentation table you built in 2.2.

Step-by-step: writing the upgrade plan

The scenario deliverable: a written upgrade proposal the team can defend line by line.

1. List the constraints. The hard requirements: bandwidth, distance, interference, mobility, budget.
2. Pick the device. Match the class to the need, then sanity-check cost against benefit.
3. Pick the medium. Copper under 100 m for anything fixed; fiber for long runs; wireless only when the device must move.
4. Make the addressing call. Static or a DHCP reservation if other devices must find it; DHCP for everything else.
5. Re-test every line against every constraint. Four of five is a fail; name the constraint that kills each reject.
6. Update the documentation. New device, new row: MAC, expected address, address type. The 2.2 table stays alive or it dies.

Worked examples

The render station

Request: export 4K video, push 40 GB files to the file server, fixed desk 9 m from the switch, congested Wi-Fi, mid-range budget.

Device: desktop. Sustained exports are its profile, and nobody asked for portability. Medium: copper Ethernet: 9 m is far under the 100 m rule, and a dedicated wired link is immune to the congestion that would choke 40 GB transfers. Addressing: DHCP; the station is a client nobody needs to find. The distractors each satisfy most constraints: the laptop on Wi-Fi adds portability nobody requested; the desktop on Wi-Fi saves one cable and inherits the congestion.

The annex link

Request: connect the library annex, 250 m away, carrying all its traffic, one-time install budget approved.

Medium: fiber. Work the eliminations: copper's 100 m limit kills it at 250 m, and a wireless bridge through exterior walls and weather fails reliability. Fiber covers kilometers at the highest speeds; its one drawback, cost, is the constraint the approved budget already absorbed. One distance number eliminated two of three media.

Practice: Upgrade Architect

Warm up with three sample questions, then work the request stack, where several options satisfy most constraints and one satisfies all.

Three free sample questions

1. A clerk scans inventory barcodes in every room on the hall, uploading each scan as it happens. Which device and link?

Show answer

A tablet on wireless: mobility-first work, small uploads, and only wireless moves with the clerk (EK 2.3.A.1, 2.3.B.4). Address by DHCP.

2. Which medium is cheap, good for about 100 m, and immune to Wi-Fi congestion, but keeps the device at a jack?

Show answer

Copper twisted-pair Ethernet (EK 2.3.B.2). That cheap, fast, fixed profile wins most short runs.

3. The shared printer must keep one address forever, but you want DHCP managing the whole network. What is the move?

Show answer

A DHCP reservation: the server always hands the printer's MAC the same address (EK 2.3.C.3). Fixed address, zero hand-typed configuration.

Now the full request stack, shuffled every run.

Using AI to draft the plan, safely

Paste the constraint list into an AI assistant and a tidy device-link-address table appears in seconds. Use that. Then verify each line: the characteristic AI failure is a confident recommendation that satisfies most constraints and quietly misses one.

The verification pass is elimination run in reverse. For each line ask: which constraint would kill this? "Static IPs for all 30 laptops" sounds tidy and inverts the addressing rule; hand-typed addresses at scale are how conflicts get created (EK 2.3.C.2). "Wi-Fi for the file server to save cable costs" satisfies budget and fails bandwidth and findability. AI drafts; the technician verifies. That division of labor is a graded skill in this course.

Key terms

Endpoint device

A device users work on or through: desktop, laptop, tablet, phone, printer, scanner, smart device.

Transmission medium

What carries the signal: copper twisted pair (electrical), fiber (light), or wireless (radio).

Twisted-pair Ethernet

Copper LAN cabling (Cat5e/Cat6): cheap, about 1 Gbps, reliable to about 100 m per run.

Fiber-optic cable

Glass strands carrying light: fastest, longest reach, highest cost; backbones and ISP links.

Shared airtime

Every device on an access point splits the same radio capacity; more devices, less each.

Static IP address

Set by hand, once; never changes. For devices others must find.

Dynamic IP address

Assigned automatically by DHCP; may change. For everything that roams.

DHCP reservation

A DHCP rule tying one MAC to one address: automatic assignment, permanent result.

Constraint matching

The selection discipline of this topic: the right option satisfies ALL stated constraints.

Frequently asked questions

Is a wired connection better than wireless?

For anything that stays put, usually yes: a wired port is a dedicated link, immune to congestion and wall loss. Wireless wins exactly one constraint, mobility. Decide by whether the device moves.

How far can an Ethernet cable run?

Copper twisted-pair Ethernet is reliable to about 100 meters per run. Past that, signal quality degrades; long runs and building-to-building links are fiber territory.

Why not use fiber everywhere if it is the fastest?

Cost. Fiber wins speed and distance and loses on price. For a short fixed run, copper delivers 1 Gbps for a fraction of the money. Fiber earns its cost on backbones, long runs, and ISP links.

Why is the Wi-Fi slow when lots of people are on it?

Wireless is a shared medium: every device on an access point splits the same airtime. Thirty active devices each get a slice of one radio, while each wired desktop keeps its own dedicated link.

Which devices should have a static IP address?

Devices others must reliably find at the same address: the printer, the file server, security cameras, and the router. Almost everything else belongs on DHCP.

What is the difference between static and dynamic IP addresses?

A static address is set by hand once and never changes. A dynamic address comes from DHCP automatically and can change at lease renewal. Static is for findability; dynamic is for convenience and scale.

What is a DHCP reservation?

A rule that makes the DHCP server always hand one MAC the same IP address. The device stays a normal DHCP client, but its address never changes.

Should I buy a desktop or a laptop?

Match the need. Heavy work at one desk favors the desktop: more performance per dollar, upgradeable parts. A laptop's premium buys that work in more than one place. If the job is mostly movement, a tablet or phone fits better.

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