But what is the differnce if I get a reseller? Do they have their own fair use policys? Or do they use the same throttling as BT?
You are probably unaware that there are three different parts of BT involved in broadband supply in this country. BT Retail, BT Wholesale and BT Openreach.
BT Openreach own and maintain the exchanges and the telephone lines to premises. We can ignore them for the minute as not really relevant to what you need to know.
BT Wholesale run a system called IPStream - also known as ADSL Max, running over those lines. This is the up to 8Mbps service.
They then sell this service to ISPs. BT Retail who sell BT Broadband to the public is just one ISP amongst all the others (broadly speaking). So other ISPs are not re-selling BT Broadband as you know it and to call them resellers is incorrect. They are
retailing the wholesale product just like BT Retail. Sainsbury's retail Heinz baked beans and so do Tesco as a rough analogy.
An ISP has to have equipment called a Central at its premises to receive the traffic from all their customers throughout the country. They need many of these as a Central has a maximum throughput of 622Mbps. As you can easily see that won't handle many customers running at 8Mbps. A Central costs over £1m rental per year. So given broadband prices, things don't add up.
The reason it works is that not many lines work at 8mbps in practice due to length, as you know. And not many users run at full line speed for more than a second or two in a minute. When you are browsing, you download a page in a fraction of a second then read it for several and your connection is idle.
That's why P2P and iPlayer and streaming video screw everything up. The Centrals at the ISP can't cope with simultaneous constant data flow to everyone.
That's the structure.
The difference between ISPs is the number of Centrals they have compared to their number of customers. Basically they allow a number of kbps per customer (I have seen 32kbps mentioned for one ISP) based on experience or what their accountants tell them they need to make a profit, as being the average rate used by a customer over the time they are using the internet.
They multiply the rate per customer they will provide by the number of customers and divide by 622Mbps. Then rent that number of Centrals. (Obviously it is rather more complicated than that but the principle is there - just in case any purists are offended).
So an ISP that allows more per customer is likely to provide a better throughput when things get busy. To do this they generally have to charge more. Though some charge quite highly but still allow a low average usage and just pocket the profit. For example BT Retail.
As a result, to stop everything clogging up completely ISPs like BT Retail have to throttle (traffic manage) their customers in one way or another - there are several methods.
The ISPs john2007 lists provide adequate average usage per customer to maintain acceptable speeds without throttling, partly by accepting lower profit margins and partly by having a pricing structure that is fine for lite or moderate users, say up to 50GB per month or so, but is too expensive for the heavy downloaders who therefore stay clear. Thus reducing the constant streaming needs on the Centrals and allowing unthrottled, lightly congested traffic through them.
The comparison tool on the TBB Main Site is a very good guide, though many other factors are relevant. Here is a
sample comparison including those mentioned by john2007.
If you do some comparisons including Sky you will see it is sort of mid-range. That is deceptive as it covers the very good LLU service you will not be able to get and also the BT Wholesale based (as described above) Sky Connect service, which is apparently rather poor and you should avoid.
Similarly you have to watch out with O2. Although its rating is higher than Sky, for some reason its poor BTW based O2 Access doesn't bring its ratings down as much from the excellent O2 LLU products. I advise that you don't get O2 Access.
A long post I'm afraid, but I hope a couple of readings of it will help you.
Edited by RobertoS (Fri 24-Jul-09 00:40:55)
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