cancel
Showing results for 
Search instead for 
Did you mean: 

Exchange contention? Why Now?

Community Veteran
Posts: 1,124
Thanks: 4
Registered: 14-08-2007

Exchange contention? Why Now?

I've been max'ed, sync is solid at 8200, and msr is 8000.

In the mornings I get good speeds (around 5500)
In the evenings I am getting normally around 1500 - sometimes less.

I am assuming this is exchange contention - my quesion is, why now. Before MAX, my connection was rock solid at 2Mb/s, and I always got speed tests in the range of 1800 regardless of the time of day.

Why is it with max, that exchange contention kicking in. It shouldn't be particularly because of max, since the speeds are dropping to below pre-max speeds. VP capacity at the exchange (Alsager) is green. The only two explanations I can think of are:

1 - Max connections are contended in a different (lower priority?) way at the exchange

2 - As people are upgraded to max, there are more people moving up from 1Mb/s connections or lower because max offers higher speeds on long lines. This is putting more pressure on the exchange backhauls.

Any other theories?
17 REPLIES
JonathanW
Grafter
Posts: 2,648
Registered: 02-10-2007

Exchange contention? Why Now?

Most likely the latter of your two theories is going to be the case, as even though BT are going to be giving the majority of people on exchanges speeds three or four times faster than what they've had before, the backhaul capacity won't be increased by the same ratio. Which means that at peak times the speed of your connection is going to drop back down to the pre-max levels.
glloyd
Rising Star
Posts: 1,652
Thanks: 20
Fixes: 1
Registered: 06-04-2007

Exchange contention? Why Now?

Well how daft is that. What's the point of having faster sync speeds if there is not the capicity to use them?
JonathanW
Grafter
Posts: 2,648
Registered: 02-10-2007

Exchange contention? Why Now?

Well, they're BT's exchanges, and its down to BT to sort out the backhaul capacity between them and the ISPs. If they choose not to increase it in line with the speed upgrades, then that's their choice to make. Though as I've said above, off peak you should get good speeds through your connection, in exactly the same way that people do on regular ADSL in a heavilly contended exchange.
mitchell20
Grafter
Posts: 424
Registered: 30-07-2007

Exchange contention? Why Now?

Yep contention is a big issue with MaxDSL.

My MSR has gone upto 8000 this morning and even after an equipment re-boot, I'm getting slower line speeds now (2742 kbps) than I was during the day last week when my MSR was 5000. I did a speed test Thursday afternoon and got 4333 kbps.

Dont get me wrong, I'm not complaining though Smiley Still paying less for a faster service than a lot of other people are.

BT must be aware of this issue, especially as more and more users get MaxDSL.
glloyd
Rising Star
Posts: 1,652
Thanks: 20
Fixes: 1
Registered: 06-04-2007

Exchange contention? Why Now?

Yes I know it's down to BTw but how crazy is it to increase the available speed without updating the network to cope with it. Makes no sense at all.
N/A

Exchange contention? Why Now?

this is geting stupid...during off peak we are at work at peak time we are at home hence we wnt be able to enjoy the faster speeds that much are we now?

BT has major issues
N/A

Exchange contention? Why Now?

Wait till cable rules the roost Tongue
ADSL is so much of a con these days. Advertise all this fancy speed and unable to provide or sustain it when its needed.

*giggles.
N/A

Exchange contention? Why Now?

Quote
Dont get me wrong, I'm not complaining though Smiley

Well I am. I've been happily getting a solid two meg for the last couple of years, and since being 'upgraded' I'm now seeing speeds below 1 meg. Fair enough, I always expected backhaul capacity to limit throughput to some extent, but this is ridiculous:

Downstream 765.8 Kbps ( = 0.7 Mbps )
Upstream 189.8 Kbps ( = 0.2 Mbps )

That's despite being synced at the full rate with excellent SNR and attenuation.
Community Veteran
Posts: 1,124
Thanks: 4
Registered: 14-08-2007

Exchange contention? Why Now?

It can easily be tested with a BT speed test. If this is just as slow, then the problem is exchange contention.

If not, then it is +net problems.

May give it a go tonight.
N/A

Exchange contention? Why Now?

we use broadband heavily - but for browsing, software maintenance, e-mail, mild telework. So our overall useage is fairly small (5G/month max). Before MaxDSL we had 2Mbit/sec with very little drop due to contention. Now we have 7Mbit data rate - rock solid since first day of Max - zero errors. And upload has increased to nearly 2X its old value. So well done BT for that. BUT our data transfer download rate 8-11pm is typically 1Mbit/s or less - recently for a period of 2 hours it was <500kbits/s.

So the switch to Max has actually reduced our data rate substantially peak times. We were happy enough on 512K so I cannot say it is a big deal. But still, if the result of technology allowing everyone to download DVDs & CDs (which we never do) and watch streaming tv (which we also never do) is to reduce peak time effective contended bandwidth to < 512K, as I fear it may be, it seems a bad deal.

I don't expect to get something for nothing - but at 5G/month and Premier service we pay a decent amount per Mbyte transferred.

Unfortunately exchange contention can't be solved through PN management policies (which unlike some subscribers, for obvious reasons, I am very much in favour of). It would require all ISPs to have consistent policies to keep decent data rates (say 1Mbit down) at peak times as DVD download becomes more usual.

I am afraid that work users like us will end up subsidising TV watchers.

Well, end of rant - perhaps my worries are groundless and extra capacity will be put in to take the additional load.

Best wishes, Tom
glloyd
Rising Star
Posts: 1,652
Thanks: 20
Fixes: 1
Registered: 06-04-2007

Exchange contention? Why Now?

You would think that if BTw want to compete with the LLU and cable companies they would improve their own network. It seems sensless to me for BTw to spend a fortune upgrading exchanges so you can, in theory, get higher speeds then don't update the network to cope. Maybe they are waiting for OFCOM to force their hand again.

It also seems to me to be false advertising for them to say you have an 8meg connection when you are never likely to get anywhere near those speeds.

Quote
Wait till cable rules the roost Tongue
ADSL is so much of a con these days. Advertise all this fancy speed and unable to provide or sustain it when its needed.

*giggles.
N/A

Exchange contention? Why Now?

Quote
Unfortunately exchange contention can't be solved through PN management policies

Assuming the speed problems really are due to exchange backhaul contention. We're just assuming that at the mo. I have friends with max connections with other ISPs performing much better than mine, but they're on different exchanges so that doesn't necessarily prove anything either.....
Community Veteran
Posts: 1,124
Thanks: 4
Registered: 14-08-2007

Exchange contention? Why Now?

Can easily be tested with a BT speed test - may check it tonight.
JonathanW
Grafter
Posts: 2,648
Registered: 02-10-2007

Exchange contention? Why Now?

Yes, as collinet already mentioned, the best way to rule us or any other ISP out of the equation when it comes to traffic slowdown is to run the BT speed test, details of which are available here if you're unsure how to make use of this facility.