The Internet Explained - Bandwidth

Published: 01 February 2013

BT recently announced its plans to get rid of bandwidth caps and traffic management on all but their entry-level broadband packages.1 We ask the questions: ‘What is Bandwidth?’; ‘What is Traffic Management?’ and ‘What does it mean for me?’.

What is Bandwidth?

Bandwidth is a computing term that is tossed around by providers and users alike, and sometimes we don’t fully understand what we mean.

There are actually two distinct definitions of bandwidth:

Bandwidth as Network Capacity (BANC)

You can think of The Internet as a series of tubes2 – your computer talks to all the other computers on the Internet via linked connections that can be thought of as pipes or tubes. When you ask for the Google homepage, your computer sends a request through those pipes to Google, who answers your request.

When we talk about Bandwidth as Network Capacity (BANC), we’re referring to how many connections can your ‘pipe’ send and receive at once. Think about a garden hosepipe – the bigger the hose, the more water you can water with!

Internet providers often measure this in ‘Mb’. Obviously, the higher the number, the quicker your connection should be.

Pipes that flow in both directions...

Unlike your garden hosepipe, the pipe that connects you to the Internet flows in both directions – known in technical speak as ‘upload’ and ‘download’. Upload is from your computer to the Internet, and download is from the Internet to your machine.

Internet providers usually only quote the download speeds as these are the ones that visually determine how fast the Internet ‘looks’. Unfortunately, upload speeds are becoming increasingly important. Whenever you post a picture on Facebook, upload a video to YouTube, or even have a Skype call with your friends, the performance is affected by your upload speed.

Next time you look at broadband providers, and you do a lot of Skyping, uploading to YouTube or Facebook or photo sharing site - enquire about their upload speed.

Bandwidth as Consumption (BAC)

There is a second definition of Bandwidth – that as consumed bandwidth (CB). What we mean here, is when you leave your garden hose on all day – the total amount of water that went through the pipe in the day is how much you consumed. The same applies to your Internet connection – when you ask for web pages, watch YouTube videos etc, you are consuming bandwidth.

Internet companies often put a ‘bandwidth cap’ or limit on how much you can download or upload in a specific time period.

What is Traffic Management?

Traffic Management (or traffic shaping) is a technique of limiting how much bandwidth you can consume by slowing your network capacity, or download rate.

Virgin Media have an extensive traffic management policy3, whereby they restrict your connection speed when you consume a certain amount of bandwidth. When exactly this occurs, depends on how much you pay (of course!), but most packages have limits on them.

So what happens when you hit this artificial limit? Well, you’ll probably notice if you’re watching YouTube or iPlayer, as your videos will stop and stutter – often ‘buffering’ for several seconds before they begin playing again. If you’re having a Skype video call with your family, they’ll probably notice it first, as your picture will ‘pixelate’ making you look like something out of Tron.

What does it mean for me?

You may have noticed that Internet providers claim that traffic management only affects a small percentage of their ‘heavy users’. This is not necessarily true – let’s take an example of the Virgin Media ‘XL 30Mb’ package between 4pm and 9pm (5 hours) and see just how easily you can hit the ‘heavy user’ stereotype4:

Activity

Consumed bandwidth

Remaining in limit (3500MB)

Watching iPlayer HD for 1 hour

1750MB

1750MB

Surfing the Internet for 2 hours

300MB

1450MB

Watching YouTube for 45 mins

700MB

750MB

Listening to Spotify or Internet Radio for 1 hour

350MB

400MB

Download 1 album of music from Amazon

200MB

200MB

Windows Update / Security Software Updates

200MB

0MB

Obviously, you wouldn’t download music albums every evening, but this is just an example – Skype video calls for instance will let you hit this limit even more easily!

Also, this is usage for just one person – if you have children or another person in the house who is also browsing the Internet, or watching YouTube, you’ll hit the limit even quicker!

So BT’s announcement that it is doing away with any traffic management, shaping or bandwidth limits really is a big deal for families and so called ‘heavy users’. Now might be the time to ring up your Internet provider and switch!

1 Original source: http://www.btplc.com/News/Articles/Showarticle.cfm?ArticleID=87EF70E6-C043-487D-9D0A-C17E79BA559E

2 The internet as explained by a US senator: http://www.youtube.com/watch?v=f99PcP0aFNE

3 Virgin media traffic management: http://help.virginmedia.com/...

4 Figures correct as of 2013-02-08


© PhotonIT February 2013