Monday, November 6, 2017

Internet Bandwidth: More computers = less for everyone

This is the first post in an occasional series on factors affecting internet access in public libraries. This information should apply anywhere where internet is offered.

Many libraries in Alaska face slow internet. One common reason is because there are too many devices (computers, laptops, smartphones, etc) for the amount of bandwidth a library has.

When you buy internet for your library, say 3x3 Mbps, that speed is delivered to your library wall. It is then available to be split up among your library computers and anything connected to your library’s WiFi network. 

Assuming that there are no tweaks to your network, you can find out how much bandwidth is available to each computer/smartphone/tablet connected to your network with this formula:

(bandwidth purchased) x 1024) / (total number of devices connected to your network) = current level of kbps per user

For example, let’s say that you purchased 3x3 Mbps for your library and you have two public computers. Each user would get:

(3x1024)/2 = 1,536 kbps per user – This speed for the two computers is excellent and should allow people to do most activities, including movie streaming, if you allowed that sort of thing. 

BUT. Let’s say you have a WiFi network and you also have five people out in the parking lot with smartphones or laptops. Now our calculation looks like:

(3x1024)/7 = 438 kbps per user – Here you have the same bandwidth delivered to the library wall, but because you have seven people working with it, each user only has 438 kpps worth of bandwidth. This is bad. It’s below the Edge Initiative’s recommendation of 512 kbps per user in order to deliver basic web browsing and e-mail. It’s very likely that all seven of your internet users are going to have unhappy experiences. 

Some libraries only have 1.5x1.5 Mbps for internet. What does their bandwidth look like for those two public computer users and five wifi users? Here’s the sad calculation:

(1.5*1024)/7 = 219 kbps per user.  At this speed, a typical cell phone photo of 4 MB would take two and a half minutes to download. It is unlikely anyone on this network is having  a positive experience. Yet the ISP has delivered their promised 1.5x1.5 Mbps to the library. 

If this is the source of your bad internet, your main two choices are 1) Buy more bandwidth (if you can afford it) or 2) Limit the number of devices that use your network. You could also tweak your network to block some usages or prioritize one computer’s access to bandwidth, but this won’t get you as much relief as either limiting devices or getting more bandwidth. Your Internet Service Provider (ISP) can offer advice on limiting or tweaking. If you are a library, you may also contact the Online With Libraries (OWL) program for advice on tweaking your network.

If you have questions or comments on this post, we'd love to hear them.

Reference:  

Edge Initiative Article
Benchmark 9: How much bandwidth does my library need?
By Samantha Becker, Sofia Leung, and Robert Bocher


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