Internet contention ratio

[Bellerophon86]

Hi All,

Can some please clarify how contention ratios actually work? I understand the contention concept but not sure how it's actually implemented in SA. This is taken from wikipedia:

'One of the issues with a stated contention ratio is that it is not, on its own, adequate for comparing services. There is a huge difference between 1000 users each on a 2Mbit/s service sharing a 40Mbit/s pipe, and 50 users each on a 2Mbit/s service sharing a 2Mbit/s pipe. In the latter case two users trying to download at the same time means each get 50% of the speed. When there are a 1000 users it would take 20 users maxing out their 2Mbit/s link at the same time to show any congestion. However both of these would be quoted as 50:1 contention...'

If I have a 4Mb ADSL connection with a contention ratio of 4:1, surely it does not mean I should only expect 1Mb.

Thanks

 

[Wyzak]

If I have a 4Mb ADSL connection with a contention ratio of 4:1, surely it does not mean I should only expect 1Mb. Thanks

No, if that is the case you should be guaranteed atleast 1Mb if all the other users are using it to their capacity. If none of the other users are online you can expect 4Mb.

ADSL contention ratios are at least 20:1 on Telkom's side and the real ratio is probably closer to 50:1 if you add the ISP etc.

 

[Bellerophon86]

No, if that is the case you should be guaranteed atleast 1Mb if all the other users are using it to their capacity. If none of the other users are online you can expect 4Mb.

Thats what I meant...

In the case of the 50:1 ratios, so if I download at full line speed (which happens quite often) you saying that 49 people in the my "pool" is not using the internet? To me that just sounds unlikely.

 

[Wyzak]

Thats what I meant...

In the case of the 50:1 ratios, so if I download at full line speed (which happens quite often) you saying that 49 people in the my "pool" is not using the internet? To me that just sounds unlikely.

Yes that is how contention ratio works, provided that there is unlimited bandwidth available at the other side of the pipe (where you are downloading from). At the specific instant that you are getting full line speed, the other people are just idling.

 

[Chevron]

Thats what I meant...

In the case of the 50:1 ratios, so if I download at full line speed (which happens quite often) you saying that 49 people in the my "pool" is not using the internet? To me that just sounds unlikely.

Most people in SA don't download though. they Facebook and read news24. 50:1 sounds about right.