How Dial-up Acceleration Works

Nowadays, compared to other ways of connecting to the Internet, normal dial-up access can seem incredibly slow. Given that, it was only a matter of time before ISP companies found ways to improve dial-up speed, which is what dial-up acceleration is about. But how exactly does it work?

For a normal dial-up connection, when you try to access, say "www.yahoo.com", your ISP searches for the Web server hosting the page. After it finds the Web server, it connects you directly to it and the page download starts.

For dial-up acceleration, or high speed dial-up, the difference is that instead of directly searching and connecting to a Web server, your page requests first go to a server on your ISP side called an acceleration server. Now when you search for a Web page, your computer "tells" the acceleration server what it wants. The acceleration server then uses a broadband connection to search for and download the page. The acceleration server then passes it on to your computer.

At this point in time you might be asking, "If my dial-up access is already so slow when connecting directly to the Web server, won't introducing the acceleration server between them make it even slower? After all, my computer still downloads the same way whether it's from a Web server or an acceleration server."

Ah, but the key to dial-up acceleration is actually in how the acceleration server passes the information on to your computer. Some of the methods used are employing file compression, filtering and caching.

For speeding up dial-up access through file compression, the theory is pretty straight forward. Information that the acceleration server retrieves from the Web server that can be compressed is compressed. The data is then passed on to your computer. This helps to improve download speeds and is known as on-the-fly file compression. Not all data can be compressed using this method though. Files like MP3 files have already been compressed and so download speeds won't be improved. Secure Web pages have encryption built in and this renders compression impossible.

For filtering, what high speed dial-up providers do is that they have included in the software they send to subscribers a program that recognises pop-up ad requests and blocks them. Not having to download the ads mean fewer things to download and translates to faster connection times.

For caching, the acceleration server stores frequently requested Web pages in its memory. Suppose some other subscriber had requested for "www.yahoo.com" before you earlier in the day. Now when you put in your request, the acceleration server just retrieves the data from it's memory and passes it on to your computer.

These are just some of the more common methods. Some other methods used are optimising the code in certain documents before passing them on to the subscriber and using link prefetching, which means using browser idle times to download documents that the user might want in the near future.

Hopefully, this article has given you a better understanding of how dial-up acceleration works.