Computer Networking · Beginner level

Beginner level · Module 5: Small Office Network Design · Lesson 1 of 3

Requirements and Bandwidth

Find out what the office needs and how much internet capacity to buy.

In this lesson you will

  • Gather network requirements
  • Estimate bandwidth needs

Key concepts

users and devicesapplicationsbandwidth estimateheadroom

The lesson

Start with requirements: number of users and devices, rooms, applications (video calls, cloud files, backups), security needs and budget.

Estimate bandwidth from what people do at the same time: simultaneous video calls, browsing users and backups, then add about 30% headroom.

Compare the estimate with ISP options and consider a backup connection if the internet is critical.

Step by step

  1. Interview the office about needs.
  2. Count simultaneous activities.
  3. Calculate bandwidth with headroom.
  4. Compare ISP options.
Worked calculation

How much internet bandwidth does a 25-person office need?

Estimating the busiest moment, adding headroom and choosing a package.

Busiest-hour estimate for an NGO office (illustrative rates per activity)
ItemWorkingAmount
Video calls at the same time12 calls × 1.5 Mbps18 Mbps
Web, email and cloud documents40 devices × 0.25 Mbps10 Mbps
Cloud backups running2 backups × 5 Mbps10 Mbps
Busiest-hour total18 + 10 + 1038 Mbps
With 30% headroom38 × 1.349.4 Mbps

Explanation

Bandwidth is sized for the busiest moment, not the average: what people do at the same time. Video calls dominate.

With about 30% headroom for peaks and growth, a 50 Mbps package fits. Scheduling backups out of office hours would cut the need to about 36 Mbps.

Check your understanding

18 + 10 + 10 = 38, and 38 × 1.3 = 49.4.

Practice activity

Write the requirements and bandwidth estimate for the project.

Expected result: A justified bandwidth figure and ISP recommendation.

Check your understanding

  1. Why add headroom to a bandwidth estimate?

    Show answer

    To allow for peaks and growth.

  2. What drives bandwidth needs most?

    Show answer

    What people do at the same time, such as video calls.

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