aa.net.uk Broadband - Broadband you can work with

Skip to Navigation / Skip to Content

Knowledge base Speed tests

One of the issues with a fast internet connection is that you realise how slow some of the internet is. The Ethernet services we provide have no delays or congestion between you and high speed transit providers in our London data centre racks, so they are fast as you can get for a general internet connection. There are a few points to bear in mind when you have a fast internet link.

  • Speed tests sites can be busy anyway but most are not designed to measure speeds of lines much above that of broadband so if you have even a 20Mb/s Ethernet service you may see lower results on speed tests. One trick is to do more than one speed test at the same time and confirm you can get the overall speed you expect on your line.
  • TCP window. The way TCP works means that it has buffering for in-transit data. Even broadband links can have issues with these buffers not being big enough. Ethernet links are normally local meaning delays of micro seconds in traffic going from one machine to another. However, our Ethernet services work over the whole country and this takes milliseconds. A millisecond is not long, but it hundreds to thousands of times longer than you would find on a LAN. As such a data transfer on a high speed link can be limited by the buffering (TCP window size) on the computers at both ends. It is worth trying several transfers at the same time if you are trying to get the most total data transfer speed out of your link.
  • Slow servers. Many services that you connect to are either (a) very popular and so limit data transfer per connection in some way, or (b) connected to the internet on a link that may be slower than you have, or (c) are simply not very fast computers. This can mean data transfers are slower than you expect. The target for most people running services is that people with broadband can access them quickly. If you have a much faster link you can start to see some of the limitations in the servers that people have on the internet.

The key thing is that the link in to the internet is the guaranteed speed you have purchased with no sharing and no slowing down or congestion. Any issues you see with speed are likely to be on an individual transfer for all the reasons listed above. Having an office full of people all using the internet at the same time separately transferring email, web traffic, etc., will be able to make full use of the link.

Some example speed tests can be found at: