Understanding contention ratio's

Anyone know how to find out the contention ratio in a specific area e.g Honeydew?
 
Nice discussion, but no real explanation where the contention occurs.

AFAIK, we have:
ADSL Modem -> DSLAM -> Telkom Exchange -> Telkom Data Centre -> IP-Connect -> ISP -> Local ZA -> International

The ADSL Modem, is assigned an IP address and the next IP address that can be seen via traceroute is at the ISP.

Is there a way to check the contention ratios / loads at various points eg:
  • DSLAM->Telkom Exchange
  • Telkom Exchange->DC
  • Telkom DC->ISP

It's normal to blame the ISP for slow access, but what about the contention before the ISP - on Telkom's infrastructure?

I use 2 different ISP's (with unrelated infrastructure)
The performance when slow, is slow to both.
I have a 4Mb/s ADSL and speeds vary from 0.5Mb/s -> 3.5Mb/s on both ISP's
This seems to imply that the contention occurs before the ISP - ie Telkom infrastructure.

Is there a way to determine where the biggest congestion is taking place?
 
ISPs don't like to advertise their contention ratios but the reality is that there is contention at every step you mentioned.
Click to expand...
It's important to note, that contention exists at every step - even before you get to the ISP - in the Telkom Infrastructure (DSLAM/Exchange).
In my case, switching between ISP's and different packages Uncapped+Shaped to Capped+Unshaped to Business ADSL shows the same throughput pattern,
Regardless of the ISP / package, I get fast in the early mornings, and slow in the afternoons/evening.
This implies that Telkom is out of capacity.

It would be useful and interesting to know what percentage of ADSL slowness is caused by Telkom's lack of capacity vs the ISP's lack of capacity.
This would help in directing performance related support calls to the correct culprit.
 
Hi new to this could u guys please tell me if this info is any good ???
Modem Status
Connection Status Connected
Us Rate (Kbps) 512
Ds Rate (Kbps) 3066
US Margin 11
DS Margin 22
Trained Modulation ADSL_2plus
LOS Errors 0
DS Line Attenuation 38
US Line Attenuation 23
Peak Cell Rate 1207 cells per sec
CRC Rx Fast 0
CRC Tx Fast 0
CRC Rx Interleaved 0
CRC Tx Interleaved 0
Path Mode Fast Path


also on my isp side i have a 4meg uncapped services but on telkom i have a 3meg connection but telkom says on there system im paying for a 4meg line should i drop it to 3meg on telkom side and will it make my downloads more stable . they seem to be jumping from 10kb/s - 280kb/s they are all over the place??
 
leeloud said:
Hi new to this could u guys please tell me if this info is any good ???
Modem Status Connection Status Connected
Us Rate (Kbps) 512
...SNIP...
also on my isp side i have a 4meg uncapped services but on telkom i have a 3meg connection but telkom says on there system im paying for a 4meg line should i drop it to 3meg on telkom side and will it make my downloads more stable . they seem to be jumping from 10kb/s - 280kb/s they are all over the place??
Click to expand...

For the interpretation of SNR see:
http://mybroadband.co.za/vb/showthread.php/186156-Understanding-SNR-and-Attenuation-Rates

I've speedtested 3.6Mbps on my 4Mbps line, but due to Telkom contention, it drops to 0.2Mbps during "prime time"
Switching ISP's does not help.

AFAIK, Telkom can drop your line from 4Mbps right down to 1Mbps and charge you for 4Mbps.
See "Profile D" on
http://www.telkom.co.za/products_services/dsl/dslaccesonly.html

I like the way they state "How do these profile benefit you?" Pay for 4 and get 1.

There is no easy way to establish if Telkom contention is affecting you.
Telkom are allowed to use a 20:1 contention ratio - but I suspect they exceed that.
Use a local speed test site to test with. Check your speed early in the morning - say 5am and again at 7pm.
Use 2 ISP's - buy a 1GB pre-paid unshaped ADSL account to test with.
If you find it's fast in the morning and slow in "prime time", then it's probably Telkom that's overloaded.

In my case there is a pattern - fast in the morning, slow during "prime time" - regardless of ISP.
I'm on the Rosettenville exchange, but there are other exchanges that are out of capacity.
 
Last edited:
Differences in contention ratio

Hi all, kindly forgive me I know this was a last year post, but was searching on the net and this came up, what I want to know is if there is a difference between say a 20:1 ratio and a 1:20 ratio, I know the first means you would be sharing with 19 other users but whats the second one???
 
tendaimagore said:
Hi all, kindly forgive me I know this was a last year post, but was searching on the net and this came up, what I want to know is if there is a difference between say a 20:1 ratio and a 1:20 ratio, I know the first means you would be sharing with 19 other users but whats the second one???
Click to expand...

The correct way to express the ratio is 1:20, which means 1 pipe is contended among 20 users (1 pipe per 20 users = 1/20 = 1:20).

20:1 is incorrect, probably a typo or misunderstanding by someone not fully clued up. I'm pretty sure they mean the same thing though.
 
If i have a 1meg connection with a contention ratio of 1:1 does that mean i get full use of the 1meg bandwidth or not?
 
Haasman said:
Yea i want to know if my speed will be 1mbs or close to, on a 1mbs 1:1 contention ratio connection
Click to expand...

What I see with most providers, it would go just over 1, one of the installations i have is a 13mb 1:4, and speedtest and true test gives me close to 16mb

The otherguys 4mb and i get 5,

The contention ratio is the part from the SP to internet, and nothing todo with the last mile to your property
 
gfmalan said:
What I see with most providers, it would go just over 1, one of the installations i have is a 13mb 1:4, and speedtest and true test gives me close to 16mb

The otherguys 4mb and i get 5,

The contention ratio is the part from the SP to internet, and nothing todo with the last mile to your property
Click to expand...

The thing i was on there 1mbs home package and that is a 10:1 contention ratio and got 120kbs to 140kbs download speed that is to be expected on a 10:1 contention ratio and now Im on there business package(1:1 contention ratio) still a 1mbs connection but my download speed is still 120kbs to 140kbs
 
Haasman said:
The thing i was on there 1mbs home package and that is a 10:1 contention ratio and got 120kbs to 140kbs download speed that is to be expected on a 10:1 contention ratio and now Im on there business package(1:1 contention ratio) still a 1mbs connection but my download speed is still 120kbs to 140kbs
Click to expand...
120-140kbs on a 1Mbps service is bloody excellent.
 
You must log in or register to reply here.
Back
Top
Sign up to the MyBroadband newsletter
X