Networking a School Computer Laboratory in Bamenda
Government Technical High School, Bamenda, has converted a 12 m × 8 m classroom into a computer laboratory with 24 refurbished desktop PCs, one network laser printer and a teacher's laptop. There is no network: learners move files with USB flash drives, which has spread viruses and caused several lost assignments. The school pays for a 2 Mbps ADSL line shared with the administrative block, and power cuts occur about three times a week, lasting one to three hours. The principal has 1,200,000 FCFA for networking and expects the laboratory to support typing practice, research with controlled internet access, and printing without a queue at the teacher's desk. The room has concrete walls, two windows and no ceiling trunking. A local technician proposes a bus topology with coaxial cable to save money; a parent proposes Wi-Fi for all 24 PCs. The school also wants a simple way to keep a copy of teaching resources on the network. Advise the principal.
1. Recommend a network topology and transmission medium for the laboratory. Justify your choice by comparing it with the technician's bus/coaxial proposal and the parent's all-Wi-Fi proposal in terms of cost, performance, maintenance and suitability for the room.
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Recommendation: star topology using UTP Cat5e cable and a 24-port switch (with one or two spare ports).
- Fault isolation: each PC has its own cable to the switch. If one cable or network card fails, only that station drops; the rest of the lab keeps working. On the proposed bus/coaxial network, one loose connector or missing terminator can bring down the whole segment, and faults are hard to locate in a room with concrete walls.
- Performance: switched Fast Ethernet or Gigabit gives each PC a dedicated link, which matters when 24 learners print or open shared resources at once. Coaxial bus is shared, older technology and increasingly difficult to repair locally.
- Cost: a 24-port switch, one box of Cat5e, faceplates, surface trunking and labour can fit within 1.2 million FCFA if the school uses a local technician. Wi-Fi for 24 desktops would need several access points, adapters and careful channel planning; 2.4 GHz in a crowded room gives variable throughput and weaker security.
- Room constraints: star cabling can follow the walls in surface trunking; no ceiling is needed. Wi-Fi would avoid cable but would not solve the power problem and would add interference.
Judgement: use star/UTP as the backbone. A single access point can be added later for the teacher's laptop and a few mobile devices, but it should not replace cables for 24 fixed PCs. Keep the switch and file server on the UPS, and label every cable and port so a non-specialist can trace faults.
2. Explain how the school should provide internet access to learners without exceeding the 2 Mbps link, and how it should protect equipment and data during the frequent power cuts.
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Internet: the 2 Mbps link cannot support 24 simultaneous video streams. Configure a router with quality-of-service rules: reserve, say, 1 Mbps for administration and 1 Mbps for the laboratory; prioritise browsing and block or limit streaming and large downloads. Use a caching proxy and a local offline copy of Wikipedia or teaching videos so repeated resources do not consume the link. Allocate internet access by class timetable rather than all day, apply content filtering, and review usage weekly.
Power: frequent cuts damage hard disks and corrupt files. Put the switch, router and file server on a suitably sized UPS giving at least 15–20 minutes, so they shut down cleanly; put the printer on surge protection. Teaching PCs can be on a cheaper inverter or allowed to shut down, but learners must save work regularly. Enable auto-save, teach Ctrl+S habits, and keep shared files on a journaling file server rather than on individual PCs. Label sockets and train a laboratory assistant to power equipment down in the correct order.
Judgement: do not buy a generator for the whole laboratory within this budget; spend on clean shutdown and data protection first.
3. The school must decide between a peer-to-peer workgroup and a server-based network for sharing files and controlling access. Recommend one, giving reasons linked to the school's resources and skills.
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Recommend a modest server-based network. A peer-to-peer workgroup is cheaper and can share the printer, but it gives no central account control: any learner can browse another PC's shared folder, passwords are per machine, and backups depend on individual teachers. With 24 users, that becomes unmanageable and undermines the school's wish to control access.
A single PC running Linux with Samba, or a small NAS, can act as file and print server. It provides one set of user accounts, per-class folders, quotas, central backup and an audit trail. It also lets the school keep teaching resources in one place and restore a deleted file.
Cost and skill judgement: the school cannot afford a full domain with a trained administrator. Install a simple file server with three or four shared accounts (staff, class groups) and correct permissions, and train one teacher to manage it. Keep the server on the UPS and back it up weekly to an external drive kept in another room. This gives most of the control benefit without the cost of an enterprise system.