In a previous article I gave links to some
bandwidth meters where you can measure the maximum download and upload speeds of your Internet connection. If you run any of those tests you would have noticed that the result you got is less than the one advertised by your ISP as the "maximum speed".
Transmitting data over an ADSL connection has an overhead of approximately 13-14%. Therefore to calculate the real maximum speed that you can download over a given ADSL connection you need to subtract that 13-14% overhead from it.
For example with a 1Mbps connection the transfer rate is 1024Kbits (or 128Kbytes) per second. However that includes various overheads that are not part of the data you are downloading. If you subtract those overheads then the real maximum speed you can download with over such a connection is 840Kbits (or 105Kbytes) per second.
This website has a nice interactive table that gives the real maximum download speeds for several popular Internet connections.
If you can usually download with speeds near the real maximum speed then you know that you get what you pay for. If however your download speeds are often much less than that, then there is a problem. The problem can be with your equipment, your ISP, the servers you are downloading from or anywhere in between.
This article has a nice overview of the reasons why you might not be able to achieve the speeds that you should.
Additionally, some Internet Service Providers implement what is called "traffic shaping". In the future I will write a separate article about traffic shaping, since it is an important issue that can often determine the quality of the services that an ISP provides. For now lets just say that many ISPs will not let you use your connection at maximum speeds for as much as you want in any way that you want. For example, while you might be able to download over the web at full speed, your peer-to-peer downloads might be throttled to a much lower speed by your ISP.
In Cyprus,
Cytanet (Netrunner) is the ISP that implements the most aggressive traffic shaping, plus the maximum download speed with this ISP is often much less than what it should. These are some of the reasons why I do not recommend this ISP. On the other hand, ISPs like
Netway,
Wavespeed and
Otenet seem to have enough bandwidth available and, for the time being at least, allow their clients to utilize their Internet connection without any severe restrictions.
