Introduction to Bandwidth

Whenever you look for web services of any kind, you are presented with a bunch of numbers for something called Bandwidth. What is Bandwidth? What does it do for me in the context of web hosting in particular?

Technically: in computer science the term Bandwidth is used to describe the ability of a cable to carry information. A high bandwidth cable can carry lots of information in a given period of time. A low bandwidth cable carries less information in the same period of time.

The most common analogy is the maximum rate of water flow in a river: If a river is very wide and very deep, many millions of cubic feet of water can pass a given point in the river in a given period of time. By contrast, a smaller river will pass far less water in the same period of time.

When you are buying web services, though, you are just given a number of bytes per month. Strictly speaking, this is not really bandwidth at all - it's the number of bytes of data transfer per month that are included in the base price of the service. There's a difference between the speed at which the data can travel and the total amount of data that can travel without additional charges - but the two are related and it's a good idea to understand them.

Note that these issues are probably not very important when you setup your first web site. They become more important later as your content grows and you start offering larger amounts of information to more viewers.

You already have plenty of personal experience with this concept: If you go to McDonalds and order a Chocolate Frosty, you are given a thick straw that you can use to suck up the shake. If the straw was thinner you would have to wait longer to suck a mouthful of shake through the straw. This could get annoying! If the straw was thicker it would be easier and take less time to get each mouthful. If the straw was really much thicker - you wouldn't care. There's only so much shake you can fit into your mouth and you can only swallow so much shake in a day. However, if there were two of you trying to drink from the same cup you would prefer to have two straws - it's easier that way and, in a sense, not much different from having a really, really thick straw.

The shake is not much different from your data. The thinner straw is said to have less bandwidth. The thicker straw has more bandwidth.

Page Size

So, how does all this relate to a web hosting account?

In practice, when somebody types the address of your web site into his browser, the web server will respond with the text of your home page. This might be a very small text file; let's say that it's 25k bytes for this example.

The text of the home page contains references to various images that should appear. Your company logo, for example, might be needed in the upper-left corner of the page. You might have some photos of your products in various places. Perhaps a photo of a member of your staff is included in a news release.

The browser will make a list of these files that are referenced in the text of the home page. It will then request each of them from the web server and they will be sent to the browser. Let's say, for this example, that each one of them is 25k bytes and there are nine of them. This adds up to a total of 25k * 9 + 25k. There is also some overhead involved in the conversation between the browser and the web server - but we'll ignore that for now. Let's say that the total cost of the request, in terms of data transfer, is 250k bytes.

Now, let's say that there are 100 people who visit your home page every day and each one of them also visits three other pages for a total of four pages, average, per visit. This would add up to about one megabyte per visit, multiplied by the hundred visits. The total comes to approximately 100MB (mega bytes) per day.

In practice the total number of bytes per visit is usually lower and the total number of visits per day is also usually lower. This example assumes a successful web site that has developed a high level of viewership. Most web sites don't get so much traffic and the few that do only arrive at this level of success after a period of time (and hard work by the maintainers of the site.)

Monthly Traffic

If this level of traffic continues throughout the month, your estimated total traffic would therefore be approximately 3GB (three giga bytes) per month. Again, this is a relatively successful web site - lots of visitors - with lots of pages that include many graphical images.

An example

There are many web sites on the internet that publish their traffic statistics, so let's take a look at a very successful site:

The MetaMap Transfer (MMTx) web site, which belongs to the National Institute of Health in the United States, is a government web site that serves information in compressed files (mostly JAR or Java Archive format although they do serve ZIP files, too.) The page referenced by the link was found by searching for AWSTATS through Google.

Note that the total traffic on the site is (at the time of this writing, April 2008,) approximately 70,000 page views from approx. 20,000 visitors. This includes an average of just over 9 items per page (usually mostly graphics.) However, if you look carefully at the statistics, you will note something very interesting in this block of information. Note that there are approximately 1000 hits on JAR files representing 72% of the total traffic and approximately 300 hits on ZIP file representing 27% of the total traffic. This indicates that 99% of the total 1300GB of traffic from that major government web site is the result of large data files being transferred.

This level of traffic is what you would expect if you have a highly successful video podcast - approximately 5,200 subscribers downloading a 250mb video every month.

Here's the interesting part, though: The remaining traffic, only about two dozen gigabytes, is the result of the 70,000 page views and the 180,000 related hits (usually small graphic images.)

Realistically, how much traffic are you expecting on your site? If you had 20,000 visitors looking at an average of 4 pages per visit on your site, would you be happy?

Monthly Bandwidth

Remember now that you were quoted a maximum number of bytes of transfer per month. Some companies quote 1000GB, some companies quote 2000GB. Knowing that most web sites never use even 1GB per month, does it make sense to offer 1000GB for $25 per month?

It turns out that some data centers are not able to meter their traffic. Therefore, the web hosting provider is buying bandwidth from his supplier at a specified price - but his supplier is not metering the traffic. Nobody cares how much bandwidth they use. Again, the question is: Does this make sense? How does it affect you?

The answer is not very nice: If you try to send out 2000GB from your web server, you will find that it's not really possible. Web servers in environments where bandwidth is not metered are usually connected to bandwidth limiting routers that prevent the servers from sending out too much information. Worse still is the fact that some data centers oversell their bandwidth. They might promise that you can send 2000GB from your server - but then they make the same promise to far too many customers.

This has the effect of blocking the traffic: Your web site will slow down, your pages will take longer to load, you won't be able to send out 2000GB of traffic (or even less.)

At the time of this writing (April 2008,) BNT Solutions quotes a far more conservative 25GB (giga bytes) per month maximum transfer per account with an additional charge for every 10GB or portion thereof. This may seem like a huge difference, but, in practice, it's not much of a difference after all.

Our primary hosting services are located in data centers with OC48 fibre optic networks that are at or near major backbones. Our servers currently use 100mb (mega bit) ethernet ports. We also have servers in a data center with a slower connection.

This means that our primary data centers can handle whatever traffic our servers generate. Also, our servers are able to generate as much as 100mb (mega bits) of data per second. In real terms: If you want to post your podcasts on one of our servers - go ahead! We will charge you a fair rate for the bandwidth that you actually use. However, we will not impose any restrictions on the burst rate for your podcasts. This means that you can post that video of the kids playing hockey and the whole team can try to download it the same day - and they won't have any problems. Try that with a company that promises 2000GB of free transfer per month!

One of the data centers that we use (at the time of this writing, April 2008,) does not have any restrictions on bandwidth - but then again the slower connection prevents us from hosting large files in the servers at that data center. At the moment we use this center for backups only.

Summary

Bandwidth is an important consideration when choosing a provider of network services. However, the rate usually quoted is the maximum amount of data transfer per month. This is not really bandwidth at all. The most important consideration is:

  • How much data transfer can you realistically expect to need?
  • What is the burst rate? (in case you need lots of transfer in a short period of time.)
  • Did your provider oversell his bandwidth? Can you actually use the bandwidth that you have been offered?

At BNT Solutions, we offer you bandwidth that we are able to provide. We check our network connections at our data centers from time to time to ensure that our providers are able to provide the bandwidth that they have sold to us. We also check our burst speeds to ensure that we can use the bandwidth whenever we need it - so that you can use your bandwidth whenever you need it.

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