Knowledge base Burstable service
We sell two variations of internet access service - uncontended and burstable.
Uncontended
The uncontended service has a guaranteed throughput between you and us. We have ample capacity to the internet for you to be able to use your link at the full speed both ways 24 hours a day if you wish. Please do bear in mind that the internet itself is, of course, a contended service and so congestion within the internet, at remote sites and load on remote services, can all cause things to be slower than the link you have.
Burstable service
The burstable service guarantees one level of service as uncontended to us as above, but allows bursting to a higher level. This bursting capacity is not guaranteed. The link between you and us over BT is configured in the same way. Also, we only budget for your use at the guaranteed level.
However, we understand that normal internet access is bursty and a 2M burstable to 10M service is ideal for typical internet use. On average the usage will be below the 2M, but you may wish to download up upload information at much higher rates from time to time.
Apart from any congestion on the link over BT, which is relatively unlikely, we also have a shaping system in place which means that continuous use above the guaranteed rate will gradually reduce your line rate. It will never go below the guaranteed rate. It also takes some time to change (around an hour, but we may adjust this over time). Once usage lowers the rate in increased again. This means if you try and run a 2M burstable to 10M service at 10M constantly you will find that over several hours the line rate has gone down to 2M only.
In practice, unless you start running constant bit torrents, we do not expect anyone to trigger this limiting as typical internet usage does average much lower than peak usage.
Costs
Both services operate with no usage limits and no extra costs for high usage. This is one of the main reasons the burstable service has the shaping in place so as to ensure that our costs are not higher than expected for the service. With either service you can safely use it flat out with no risk of any extra bills.
Smart shaping
Whether on the uncontended service or the burstable service, we shape the traffic to the line rate. We do this because we can shape the traffic in a way that is slightly smarter than BT. We currently deploy a simple system whereby small packets are sent in preference to large packets when a link is full. This has the main effect of making voice over IP work even when downloading at full speed on your link. Whilst we do not guarantee any tagging or priority for VoIP on the line (and neither do BT) this has proved to be very effective. The alternative for VoIP is a separate etherflow, but this adds to the cost considerably.
If you need this type of shaping between your offices on etherflows then we can supply similar equipment as a router/firewall on your network. This product is due to be launched later in 2009.
