Interesting ADSL details...

[ispinsider]

Firstly, the disclaimer:

No names for obvious reasons.

Telkom obviously denies these numbers and say they are not for public release.

Read what you would like into them.

I will only post this message and return to lurk mode. One post only.

After months of meetings with Telkom to get these numbers which we needed for a product roll out to business customers the following were brought up in conversations.

Please realise that they can just as easily be right as wrong as there is so much smoke and mirrors with Telkom you can just never be 100% certain.


Now for the low down:

As we all know, certain ADSL numbers are kept strictly out of the public domain.

For every 512k ADSL Business connection Telkom provisions 32k on thier ATM cloud.

The internet access contention ratio is 128:1.

Thought this might make an interesting discussion point.

I do not work for the ISP that this IP address is.

Ciao.

 

[Highflyer_GP]

OMG 128:1 and this is for business users. imagine what a crap ratio residential users are getting

 

[Celemasiko]

contention ratio 128:1??? Thats even worst then I thought....

 

[Clipse]

well atleast we can download the internet backwards.

 

[paarlberg]

OMG 128:1 and this is for business users. imagine what a crap ratio residential users are getting

Telkom probably treats them as the same with the same ratios.

 

[P0tenc]

128:1 It's unheard of.

 

[Defender]

128:1, I really think someone if feeding you some BS information.
I'm currently torrenting 2 files from overseas on a 3gig account and am getting 21kb/s. Oh and yes I checked all the sources are from internationl non are local.

 

[Darth Garth]

128:1, I really think someone if feeding you some BS information.
I'm currently torrenting 2 files from overseas on a 3gig account and am getting 21kb/s. Oh and yes I checked all the sources are from internationl non are local.

Abuser .

 

[PostmanPot]

is it odd that i get 50 - 55KB/ps on torrents permanently?

 

[arf9999]

128:1, I really think someone if feeding you some BS information.
I'm currently torrenting 2 files from overseas on a 3gig account and am getting 21kb/s. Oh and yes I checked all the sources are from internationl non are local.

no it is possible..you just don't know how contention works. and 21kb/s is pretty ****...now if it was 21kB/s it would be slightly different.

 

[ic]

What then does it mean that I can usually get my HomeDSL192 to max out at 33kBytes/s [multi-threaded local & international, not tried P2P yet]...?

 

[Clipse]

contention only kicks in like this:

lets say there is, speculation!!!, 100mbit international bandwidth anytime available for ADSL. Then its pretty much simple maths, if 200 people on 512k download at the same time, they would all max their lines, and max the international pipe. If 400 people download max, then that would be divided by 400 and roughly 25k/s per person.

I dont know for a fact how much international bandwidth is available and I do hope more than 100mbit for ADSL, but this is a way of working out general contention. If you allways download and get full speed internationally, well, then you should be happy that not everyone on ADSL is downloading 24/7 ;-)

So basicly, if the contention on ADSL is 128:1, and the whole of the ADSL userbase(100000) is downloading 24/7, at 2000 people, you would hit 1:1 contention if we had 1gbit international bandwidth available all the time. Now 100000 people is downloading 24/7, that would put the active contention per user on 50:1 ie. 1.5k/s if everyone used 512k.

Yet again, you need to praise the fact that not EVERYONE (80% atleast) download 24/7 ;-)

 

[TheRoDent]

If we were contended 128:1, we would see serious degradation in our service. Even during daytime my 512Kb still humms, reasonably. And I don't have a business service.

128:1 is just not viable. I don't buy it.

 

[paarlberg]

Clipse is right..

The main thing is how many of your clients does it take to kill your line.. the fewer the better the chance that you will see the impact..

Say you have a normal client of 512k and you only have 2mbps of bandwidth the chance is pretty good that 1 or 2 can hurt you. If you increase that to 10mbps of BW and the same ratios, it will take more clients to hurt you.. It may be the same percentage that it takes, but the chance that all are bursting at the same time is much lower.. except when MS releases a 300MB SP for an OS.. then you might see the impact..

 

[Highflyer_GP]

how else do u explain the "cable faults" and "ny to rosebank" links going down. etc. yet pings to even telkoms site was timing out. as clipse points out it all depends on how many people are connected at any given time of the day. im not saying the contention ratio is always to blame, but why else would telkom keep it so secretive if it wasn't something this high?

 

[Peapod]

i think this is worth exploring. it blows the concept of "broadband" that telkom is touting completely out of the water. It also blows eveything they have said regarding service and service availablility to hell. Truth or not, it is worth investigating.

 

[SuperAntMD]

How exactly does a contention ratio work? I mean i understand the sharing of bandwith but who is it shared between? Do they just share it as users start using it at random or is it done per exchange ie if the contention ratio is 50:1 and 150 people are online does that mean that 3x 50:1 is being maxed out or could it be 25:1 here and 10:1 there... etc etc depending on where the people are connecting from?

 

[mbs]

If we were contended 128:1, we would see serious degradation in our service. Even during daytime my 512Kb still humms, reasonably. And I don't have a business service.

128:1 is just not viable. I don't buy it.

My experience for the past two months or so, points to high contention ratios - also on a 512 residential service, with daytime performance extrememly sucky. Also occurs intermittently, which presumably indicates patterns of usage by business users, off whatever my exchange is. What I find notable is that this was not the case previously - my naive assessment is that this is just network mismanagement, on the ISP/Telkrap's part. Ah well, this is a non-SLA service, so I'll just have to bite the bullet and swap my working/sleeping hours around, I suppose...

 

[xpuser]

Hey all!

Contention is only evil when everyone tries to be a power user and download something all the time, which never happens in real life. It is uneconomical from a telecomms point of view to get equipment that will provide everyone with full service all the time so solution?

1. Get some expensive experts to do some statistics calculations so you know what percentage MAX of your clients will use their connections all the time, how many 90% of the time, 80% etc so you have a total bandwidth figure which will be significantly less than that needed to allocate 100% bandwidth to all, ALL the time.

2. Build your network with this figure in mind but with scalability also so that you can grow or shrink the network as necessary. If it is a critical network e.g. phone system, then you HAVE to have spare capacity that can be brought online quickly in the event that everyone (80 - 90 %) for some reason is using their phone at the same time, although this capacity is seldom put aside since it is expensive and the liklihood of such a situation for any reasonable length of time is statistically slim (London Bombings; cell networks practically collapsed under load but that was due to a terrrorist attack and as soon as people calmed down, the networks started operating again)

3. In the case of ADSL, the spare capacity bit is cleverly taken care of by contention in that if you have a 50:1 ratio, then on that day when all try to download, you only have to make sure that you have enough spare capacity for everyone to have one fiftieth of what you promised them. If you run a mission critical internet connection, then all you have to do is make a special arrangement whereby you pay much more for an uncontended lineso that no matter what happens, you have your full bandwidth.

 

[freeek]

mbs .... I have to agree with you. Before telkom did that whole exchange thing making our connection to exchange or dslam or wateva drop from 2Mbps to 640Kbps everything started to be real bad.... espcially in the day..... bad surfin, bad pings, slow downloads.... Im on a business line and its terrible