ITSS WebDev Guide

Understanding this Thing Called Bandwidth

Bandwidth refers to the room available to move data. Think of it like this:

You've invited four friends over to watch movies on your state-of-the-art Home Theater system. The prime seating is on the couch directly opposite the TV screen. Your couch will comfortably seat three people, and you could crush a fourth in there if needed.

But tonight (ah yes, tonight) all four of your friends actually show up! This is unprecedented as someone always cancels. Four friends and you - that makes five. Three on the couch is comfortable, with four possible but uncomfortable, and one is still left out.

If you increase the width of your couch, more people could fit on there comfortably. If you increase the width of your couch, more people could be crammed in there as well. But to increase the width of your couch you'll need to buy a new couch!

In this scenario the data was sitting on its collective backside on the couch. In the world of the Internet, data is being moved from one location to another (this is why it's also called the "Information Superhighway"). Just like a highway it is possible to have more cars (data) on there at one time than is "comfortable." It is also possible to bring the "traffic" to a halt. The bandwidth (width of couch, number of lanes on highway) available determines how much data can be used comfortably before things slow down and eventually come to a halt.

What Determines the Bandwidth Available on the Internet?

Here's where the road gets bumpy. Bandwidth is not measured in just one place. There are many areas that affect the traffic.

The End User's (this means your) Computer

Depending upon what kind of information you want to use on your computer, its bandwidth capabilities may or may not be okay. Many computers out in the world are more than adequate to deal with text. Text (what you're reading) is small, fast and efficient. Text doesn't require much to be moved around and doesn't require much to be displayed on a monitor.

As the information to be displayed becomes larger and more intensive (graphics and multimedia), the pool of computers that can actually deal with this becomes fewer and fewer (time to buy a new computer).

Connection speed to the Internet

Many people connect from their homes with a "dial-up" or modem connection. Currently the top speed in analog modems is 56 kbps (56,000 bits per second). The FCC has an upper limit of 53 kbps, and in the real world most 56 kbps connections do well to get in the high 40's.

Why is this so? The quality of your modem, the quality of the modem on the other end of the line, the quality of your telephone line, the quality of the telephone company's telephone line, etc. all affect the top speed a modem can successfully send and receive data at. This means 56 kbps is a theoretical top speed. Your mileage may vary.

Faster connections are also available (at a higher cost, don't you know). Broadband over Power Lines (BPL), Cable modems, Digital Subscriber Line (DSL), etc. all provide an improvement in connection speed, but...

Backbone of the Internet

Having the world's fastest connection doesn't do you any good if the "Information Superhighway" can't handle the traffic. Think of a Ferrari sitting in rush hour traffic in a major metropolitan city. Five miles per hour in a Ferrari is just as slow as five miles per hour in a Geo Metro (although it is more expensive and probably more fun!).

The bandwidth of the Internet backbone can be increased just like more lanes can be added to a highway. And just like adding lanes to a highway, improving the backbone of the Internet takes time and money.

So let's say time and money isn't a problem to improve the Internet's backbone. Guess what?

Traffic on the Internet

The traffic just keeps increasing. More people are on the Internet than ever before and they just keep coming! You know this never happens with highways. When a lane is added only the same amount of cars as before use the road, right?

What if cars were designed to take up two lanes instead of one? What if your friends were all pro football players? How many can fit comfortably on the couch now? Well, we want to see more than just fast, efficient text on the Internet.

Size of the traffic on the Internet

Graphics and multimedia are really cool, but they chew up a lot of bandwidth. These are the football players on the couch. These are the "wide loads" on the highways.

Bottlenecks on the Internet

To get from here to there you may go through many "hops." Each hop is a chance to run into a bottleneck. Even if you had a direct connection to the Web page server, many other people may be trying to access that server at the same time - like going through a toll booth.

So I shouldn't use Graphics and Multimedia, Right?

Please, don't say that! Graphics and Multimedia can be a lot of fun and informative. They can also be boring and pointless. This is part of the key in determining how and when to use them. But that's a topic for another page.

Rev: bdr 07.06 xs