Broadband – How Bandwidth is Divided

On first converting from dial up to broadband, most users are completely taken by surprise by the speed of the service. Once they have hooked up all their computers and games consoles, the speed seems to have changed, sometimes drastically - yet the rate of the actual connection hasn't changed. Where is the difference coming from?

Every device that connects to the internet consumes bandwidth. Even when idle, computers and games consoles "dial home" and use bandwidth to send and receive data. A Sony Playstation 3 might not be playing an online game, but when the PS3@Home screensaver program cuts in, it fetches regular news and weather updates throughout the time it is idle, as well as submitting cloud computing data - this consumes bandwidth.

By far the highest consumption of bandwidth is Peer to Peer (p2p) software transfers, by such programs as Limewire or Vuze. These services open multiple connections with other machines, each connection handling a separate stream of data. By default, these programs allow unlimited incoming and downloading connections; each connection consumes the available bandwidth for the entire home network.

P2P software can and often is left connected even when the machine is otherwise idle, and if more than one machine is running a P2P system at a time the slowdown can be bad enough to cause page load failures in a normal browsing session. Some games also use P2P for downloading patches which can also result in network slowdown.

PCs in particular also tend to have a lot of programs checking for updates without consulting with their users first. Many of the top applications contact their software authors and download updates, even Windows itself (the second Tuesday of the month is known as "Patch Tuesday" as this is the day each month that Microsoft issue patches related to that vulnerabilities fixed that month) and depending on the size and scope of these updates this can consume large amounts of bandwidth.

Even iTunes consumes bandwidth on its own schedule, checking for podcasts that the user has subscribed to or sending and receiving iTunes Genie information to make recommendations on playlists based on the music the user has on their computers.

Additionally, there are other devices - Cameras, VoIP phones and similar devices - that can be plugged into a router and will then consume bandwidth.

The actual broadband connection never changes, and is subject to dividing its resources between all these potential requirements. The router that plugs into (or in some cases is integrated with) the modem constantly balances the various requests for information from different devices, but it only has a finite amount of bandwidth to divide up. A machine requesting more bandwidth for whatever purpose will be allocated that bandwidth in preference to a relatively 'quiet' idling machine or a turned off games console, but the re-allocation when these devices start to ask for more resources can take time to balance and take effect.

The next time your PC experiences slowdown in its connection, it is not necessarily malware on the PC. There are many factors that influence available bandwidth, and an understanding of them is to understand where on your particular network the slowdown is likely to be.

Jake is the webmaster of BredbandPriser.dk. You can learn more about him here.