Knowing the underlying performance of a broadband line is vital to setting the expectations of your customers, determining your own proposition to the market and comparing value for money.
BT have recently revised the way they describe the end user experience on IPstream again and this has particular relevance for resellers of SIP trunking and hosted voice solutions.
When IPstream was first introduced it was available in two versions. IPstream home had a contention ratio of 50:1 and Office had 20:1. In October 2005 BT realised that their network was performing a lot better than this and to differentiate themselves against LLU (local loop unbundled) providers they introduced the concept of ‘expected end user experience’. A 2Mbit/s Home line has a minimum downstream throughput expectation of 400Kbit/s and Office has 800Kbit/s. Resellers using a wholesale ISP with an uncongested business network can offer ‘equivalent contention ratios’ of 5:1 and 2.5:1, which provides a competitive edge and a unique selling point against general purpose ISPs and LLU.
There were two pieces missing at that time that have now been added by BTW; upstream contention and equivalent contention on MAX products.
Our experience has always been that BTW’s upstream network is virtually uncongested but for some reason BTW have always been reluctant to confirm this. However as part of the 21CN consultation project they have just released this graph which shows that for 99% of the time BT Wholesale’s upstream network is never more than 45% full and never exceeds 65% utilisation. This is welcome news for resellers wanting to run several simultaneous voice calls over a broadband line.
Source: BT
But what about MAX? It gets a bit more complicated with MAX due to the distance from the exchange and quality of the line. However, if the line rate is at least 2.2Mbit/s then BT says the minimum expected downstream throughput should be 600Kbit/s for MAX and 1200Kbit/s for MAX premium. This is really good news because it sets the maximum equivalent contention on Max to just under 14:1 and on Max premium to just under 7:1. BTW do not guarantee these throughputs but you can report a line as faulty if average throughputs drop below them. A word of caution, BTW do not allow reservation of bandwidth on IPStream so there is always the possibility at exceptionally busy periods that throughputs are squeezed. If you are running VOIP then make sure the ISP you are using is running an uncongested business network and is able to prioritise voice across it.
I hope this has helped to explain the changes. For further help contact Griffin Internet at whitelabel@griffin.com.
Source: Comms Dealer October.
Andrew Dickinson
