Bandwidth requirement calculation

Well I have a problem: I need to specify the minimum bandwidth that an organisation is supposed to have. Since I don’t know much about networking, I came up with this simple (and apparently logical) calculation. The problem is that it’s so simple that I’m not sure if I’ve missed something.

There is is:

  • An organiastion has: 100 computers
  • Out of these 100 PCs, 50 are continuously accessing different pages from the Internet
  • I’ve assumed that a web page is 100 KB (I know, many are much more than that but … round figures are good šŸ™‚ )
  • It’s reasonable (given that we are in Mauritius; far away from everything) that someone waits 5 seconds for such a page to download completely
  • So the number of KB/s required is: 100KB / 5 seconds = 20 KB/s
  • Given that 50 computers are accessing different pages off the Internet, the bandwidth required for these 50 is: 50 PCs * 20 KB/s = 1000 KB/s ~ 8.9Mbps (Megabits per second)

I’ve also made the following assumptions:

  • There’s no proxy in use
  • a PC is not going to access the same content twice (which means that it can’t retrieve the contents from the cache)
  • No downloads

So do you think that this calculation is ok, at least as a rough calculation? Please let me know what you think


2 responses to “Bandwidth requirement calculation

  1. the 100KB per page assumption will vary widely depending on the organisation, nature of their work, and policies in place. Like if you have at least 10 pcs continuously youtubing….then you have a problem here. Similarly, if everybody will just be viewing webpages with minimal graphics, the 100KB will then be too much. So the final estimation will vary widely. Maybe a quick on-site survey will help a lot.

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