Understanding contention ratio's

Shayd

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It seems that contention ratio's will now be important as ISP's bring out newer and newer products. Just my 2c to help those who don't understand where the ISP's are coming with these new prices.

Firstly try and understand bandwidth as a pipeline full of water that comes to your house, the municipality(ISP) has a couple of large pipelines and then connects you house and all the other houses in your street to the pipeline. The amount of people connected to that pipeline would be the contention ratio.

So the pipe has 10 people on it, ratio is 10:1. In this scenario it is unlikely you will be using the water at the same time so the water pressure should always be good. Now imagine what would happen if they put a townhouse complex on that same line and 100 people now used it. The water pressure would drop and everyone would complain.

With uncapped accounts ISP's try to determine how many people can be put on one pipeline before the "water pressure" drops to an unacceptably low level and then prices their product accordingly.

Frankly you can make an uncapped product any price you wish, it boils down to contention, lets say the raw cost of 1Mbit of bandwidth is R6750 all in.

You can make a "premium" service and content it at 10 to 1 making it R675 per user
You can make an "ok" service at 25 to 1 at R270
You can make a "basic browser" service at 67.5 to 1 at R100

All that happens is you have stricter AUP's the higher your contention ratio. You may let downloads go wild on the "premium" service and tolerate them to a lesser degree on the "ok" service but on the "basic browser" service the moment they step over the AUP guidelines you throttle the hell out of them or tell them to find a new ISP at the end of the month as you will no longer provide them service.

I hope this helps, I know the more technically minded of us take understanding this for granted but I hope it helps the rest understand why sometimes their line doesn't run at full speed.
 

Mr.Jax

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Great post.

In S.A. we're apprently at a contention ratio of 20:1, but I've always wondered, contention with regards to what exactly ??

Does the contention apply to the back-haul circuit, local backbone, international bandwidth or to all of them ?
 

william riker

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thanks, man!

i finally have a basic understanding of contention ratios...

whats the global standard, compared to SA ?
 

Guantanamo

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Sounds like fun my turn

You have a can of Coke. It costs you R7 for this can. You can sell this can to someone for R7 but they won't necessarily drink it all in one go or you can put two straws in and sell it for R3.50 to two people but if they want to drink at the same time they get less coke but assuming some law that I cant quite think of right now, they will most likely use the straws at different times. According to ICASA you shouldnt have more than 20 straws/ coke but we all know that some ISP's would find their pricing "unsustainable" at these contention ratios so they put more straws in the coke.

Lets move on to throttling vs Shaping

Ok so you have your straws and coke and someone wants to drink(HTTP) but someone else on one of the other straws wants so spit coke at a friend(P2P) the ISP can manage the network so that the drinker gets more coke more quickly than the spitter. Thats shaping ie: only certain things are slowed down

Throttling is when both the drinker and the spitter get much less than their straw can manage no matter what they want to do. Ie: all protocols are shaped.
 

grok

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This does not explain the 'hundreds of GB's' before being considered an abuser. Sure if you leave it running day & night you'd have a problem, but even at 150GB per month for a 4meg line that's like R3 per gig.
What caused the sudden flood of bandwidth or sharp drop in prices? Why wasn't this viable 2-3 months ago .. or was it a case of greedy ISP's all along?
 

Cadavre777

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A good analogy you made there Shayd. I hope this will help the lesser technically inclined understand. Maybe a mod should sticky this thread.
 

Shayd

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To Mr Jax.

When Telkom talks about contention on their lines they mean that for every twenty 4Mb users on their ADSL service they have one 4Mb link into their internal network.

Eg using my water example, for every 20 houses with 10 Litre per minute taps they will use one 10litre per minute pipeline.

In my analogy Telkom is the pipeline provider and your ISP provides the water.
 
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PsyWulf

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This does not explain the 'hundreds of GB's' before being considered an abuser. Sure if you leave it running day & night you'd have a problem, but even at 150GB per month for a 4meg line that's like R3 per gig.
What caused the sudden flood of bandwidth or sharp drop in prices? Why wasn't this viable 2-3 months ago .. or was it a case of greedy ISP's all along?
Overseas it's not entirely uncommon to have 1% of the userbase account for 30% of bandwidth usage,the other 99% paying that much for an account they only use 1gig on 1 month then 10gig the next works to subsidise those top abusers. Lots of us are questioning the sustainability of such practices as more people start thinking they're entitled to using 500gig a month indefinitely just because "i pay for uncapped so i want as much as i can all the time" - killing the viability in cross-subsidising and just making everybody's experience hellish
 

Shayd

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thanks, man!

i finally have a basic understanding of contention ratios...

whats the global standard, compared to SA ?
There are no global standards, but a general rule is that contention goes up as speeds go up.
It makes sense, a website is only so big, so if you download it on a slow service it takes time and if you download it on a fast service it loads almost instantly. The amount of data transferred is exactly the same only difference is speed.

Back to my example. if you run a 150L bath with a 10litre per minute tap it will take 15 minutes but if you fill it with a 100litre per minute tap it will only take 1:30.

British telecoms is the only place I have seen contention ratios published. For their residential users it is 50:1 and for priority or business users it is 20:1.

Please bare in mind that these are not 384k lines so the contention is barely felt by anyone.
 
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Budza

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Great post.

In S.A. we're apprently at a contention ratio of 20:1, but I've always wondered, contention with regards to what exactly ??

Does the contention apply to the back-haul circuit, local backbone, international bandwidth or to all of them ?
Should be the slowest of the three- the user will be bottlenecked somewhere, so the effective bottleneck is where the contention ratio should apply. 1GB international limited to 10MB local circuit means the users all "contend" for the 10MB. Something like that.
 

grok

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That I understand Psy, part of my question was why hasn't this been implemented before? This is not a new or radical model in any way is it?
I have a feeling this was possible long before now, yet the powers that be chose to feed us little baby spoonfuls at a time to keep the price artificially high.
Even at 50GB per month that's less than R10per gig, that's R60 less than some ISP's are still charging per gig. Not to mention the cellular providers!
Kudos for Mweb to be the one that started the flood then.
 

Shayd

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This does not explain the 'hundreds of GB's' before being considered an abuser. Sure if you leave it running day & night you'd have a problem, but even at 150GB per month for a 4meg line that's like R3 per gig.
What caused the sudden flood of bandwidth or sharp drop in prices? Why wasn't this viable 2-3 months ago .. or was it a case of greedy ISP's all along?
Ok lets go back to my example, you have a 10000 litre per day line going into 20 houses, now lets say instead of charging per litre used(eg. per gig) you just charge an access charge and say to folks use as much as you want. Most folks usage won't really be more than say 200 litres per day leaving 6000 litres per day available. For the "average" user the price is probably higher than it used to be but they get the security of getting a fixed bill per month so easier to budget and no getting cut off.

Now lets chuck in a downloader into the mix, downloaders are like the 20th guy who runs a farm on his land and has no river, he will consume the entire remaining 6000 litres all by himself and smile that his water price has gone down.

Please don't take the analogy literally as it has many technical "holes" and doesn't take into account things like caching and shaping. But to get an idea why prices dropped for downloaders, its basically due to those who don't use the net for downloading subsidizing those who do.
 

Shayd

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Overseas it's not entirely uncommon to have 1% of the userbase account for 30% of bandwidth usage,the other 99% paying that much for an account they only use 1gig on 1 month then 10gig the next works to subsidise those top abusers. Lots of us are questioning the sustainability of such practices as more people start thinking they're entitled to using 500gig a month indefinitely just because "i pay for uncapped so i want as much as i can all the time" - killing the viability in cross-subsidising and just making everybody's experience hellish
Exactly right Psy, this is why they put AUP's( Acceptable Use Policies ) in place, so if you consistently download a copy of the internet onto your hard drive they will eventually tell you to calm down or cancel your service.
 

Shayd

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That I understand Psy, part of my question was why hasn't this been implemented before? This is not a new or radical model in any way is it?
I have a feeling this was possible long before now, yet the powers that be chose to feed us little baby spoonfuls at a time to keep the price artificially high.
Even at 50GB per month that's less than R10per gig, that's R60 less than some ISP's are still charging per gig. Not to mention the cellular providers!
Kudos for Mweb to be the one that started the flood then.
Actually it's because there hasn't been much competition in the Tier 1 ISP space and as you know competition breeds creativity.
 

herbertk

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well put dude... shaping when you want to use a specific tap that the supplier doesn't like... say p2p lol... and they put a frieken nozzle in front of it... that slows it all down..
 

Shayd

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LOL I just came up with a way to explain Caching for the anaolgy.

Caching is where you use some clean water from the pipe to: take a bath, wash dishes, take a shower etc. That "used" water is stored in a big underground tank, when someone wan't to flush their toilet or use water to water the garden this "used" water is pumped out and used for these purposes.

That way the pipe has less demand on it for things that don't require clean water.
 

herbertk

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LOL I just came up with a way to explain Caching for the anaolgy.

Caching is where you use some clean water from the pipe to: take a bath, wash dishes, take a shower etc. That "used" water is stored in a big underground tank, when someone wan't to flush their toilet or use water to water the garden this "used" water is pumped out and used for these purposes.

That way the pipe has less demand on it for things that don't require clean water.
or if you have your own water tank on the roof, and you can get pre-pumped water ....
 
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