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Contention Info

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Contention Info

Just thought I'd pass on some info about contention that people may not be aware of. I used to worry that the 50:1 contention ratio meant that I could potentially get 10kbps if everyone was downloading at once (ie 512 / 50 = 10.24Kbps)

According to the website below (and a couple of others that I have researched) the 50:1 contention ratio does not refer to 512K at 50:1. Instead it refers to 10Mb at 50:1, 10Mb is the size of the pipe that BT provide at the exchange.

Therefore, even all 49 other people on your pipe were using every bit of their bandwidth at once (a very unlikely situation) then you should still be able to get a 200Kbps throughput. (10,000 / 50 = 200). This is interesting reading as it means that if you are getting a connection speed of sub 200Kpbs, there must be a bottleneck elsewhere and contention may not be the sole cause of your problems. I wonder if anyone from Plusnet support can confirm the figures above?

Anyway, this is the website that I took the information from:

http://www.the-scream.co.uk/html/resources/adsltips.html

Just thought it may be of interest to people ;-)

Jon

1 REPLY
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RE: Contention Info

Yeah, I think you're right with the figures there, which is why the business option has a contention ratio of 20:1 so that (in therory) business users always get their 512K.
However, I think it's a big and wrong assumption that a significant proportion of the 50 sharers won't be downloading all at the same time. I think the majority of BB users use it for downloading large files - afterall, that's partly the point of having it. Also, how does this assumption square with the marketeer's view of ADSL where it will be used as an entertainment delivery mechanism? If this kind of usage, particularly high quality streaming video, was to become more widely used, then the 50:1 contention model doesn't really stack up. Does it?


> Just thought I'd pass on some info about contention that people may not be aware of. I used to worry that the 50:1 contention ratio meant that I could potentially get 10kbps if everyone was downloading at once (ie 512 / 50 = 10.24Kbps)
>
> According to the website below (and a couple of others that I have researched) the 50:1 contention ratio does not refer to 512K at 50:1. Instead it refers to 10Mb at 50:1, 10Mb is the size of the pipe that BT provide at the exchange.
>
> Therefore, even all 49 other people on your pipe were using every bit of their bandwidth at once (a very unlikely situation) then you should still be able to get a 200Kbps throughput. (10,000 / 50 = 200). This is interesting reading as it means that if you are getting a connection speed of sub 200Kpbs, there must be a bottleneck elsewhere and contention may not be the sole cause of your problems. I wonder if anyone from Plusnet support can confirm the figures above?
>
> Anyway, this is the website that I took the information from:
>
> http://www.the-scream.co.uk/html/resources/adsltips.html
>
> Just thought it may be of interest to people ;-)
>
> Jon
>
>