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Conention Rations, could F9 tech suport person explain?

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Conention Rations, could F9 tech suport person explain?

Hi,
I am trying to gain a better understanding of the contention ratio concept behined the use of my ADSL connection. I know that contention ratios vary and that they are usually either 50:1 or 20:1 but what I'd really like to know is at what point in the network does contention kick in i.e. is that at the BT exchange level or at the F9 ISP equipement level?

**Also what other factors influence how the ADSL user experiences the actual bandwidth (i.e. speed & performance of his/her connection)?

Many Thanks
Ivan
5 REPLIES
Mike_Grice
Grafter
Posts: 206
Registered: 05-04-2007

Re: Conention Rations, could F9 tech suport person explain?

Quote
Hi,
I am trying to gain a better understanding of the contention ratio concept behined the use of my ADSL connection. I know that contention ratios vary and that they are usually either 50:1 or 20:1 but what I'd really like to know is at what point in the network does contention kick in i.e. is that at the BT exchange level or at the F9 ISP equipement level?

**Also what other factors influence how the ADSL user experiences the actual bandwidth (i.e. speed & performance of his/her connection)?

Many Thanks
Ivan


Hi there,

ADSLGuide's How It Works guide shows an overview of how the bits fit together. With regards to contention, you are contended at your local exchange (we have plenty of spare BT ATM transit bandwidth so you are not contended at our end).

The contentions are either 50:1 or 20:1 because you're connected to a particular piece of kit in your local exchange (a DSLAM, Digital Subscriber Line Access Multiplexer), each of which are rated 20 or 50 to 1.
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Re: Conention Rations, could F9 tech suport person explain?

So does that mean that F9 ADSL users all connected to one exchange share their bandwidth with 19 or 49 other customers depending on the contention ratio? Could these other customers be subscribers to other ISPs? Surely that doesn't mean that each group of 50 customers gets e.g. 512Kbps downstream to share? What happens if one or more customers have a faster ADSL connection? Do they take the place of a few customers?

Thanks. It's just that "contention ratio" is always used around F9s website with no explanation of what it actually is. Maybe you should have a page which answers these sort of questions.
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Re: Contention & ADSL

Hi,
Yes! I have been trying to understand the concept of contention on ADSL and as far as I can understand this, contention takes place at "YOUR" local BT phone exchange (the BT ADSL equipment uses a device called a Multiplexor and its this that deals with the contention I think?) and NOT at the F9 ISP level.

Again as far as I understand contention one large data pipe is potentialy shared amoungst 50 or 20 users, but that this assumes that not all 50 or 20 people will connect & use the bandwith at exactly the same time i.e. such a downloading etc. So if you actlually measure your ADSL conection or speed of your connection its always in a state of flux (never precisely the same speed) and the contention would help to explain some of this variation I think.

**YES! please could F9 have some support pages that explain ADSL & Contention I agree that this would be helpful.
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Conention Rations, could F9 tech suport person explain?

So I presume each group of 50 users might have say a 1MByte/sec data pipe for 50 512kbit/sec connections - if they each had a 1:1 contention, they would require a 3MByte/sec connection between them.
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Conention Rations, could F9 tech suport person explain?

selfish BT.