Exchange contention problem

Since last November, my local telephone exchange is listed as being contended and performing at below BT's accepted threshold. I've proved this using the BT speedtester facility where I've seen speeds as low as 165kbps during peak hours while at off-peak, it performs at very nearly 2mbps.

Zen can't raise a fault with BT as the exchange can perform correctly (yeah right, at 0 dark-thirty o'clock!). BT won't accept a fault directly from me because I don't have broadband service from them, even though it's completely dependent on their equipment. The date for the "exchange upgrade" is always a week in the future.

According to Zen's exchange checker page:

"The postcode XXXXXXX is connected to the Feltham exchange

According to BT's latest data the VP status of your exchange is RED.
A date of 16/02/2007 has been set by BT for the exchange to be upgraded.

This means that your exchange is running well below the performance thresholds published by BT. If you are experiencing Slow speeds then this is the most likely cause. Once the exchange has been upgraded the speeds should start running at normal levels again. If you still experiencing issues then you should contact our technical support team to carry out further diagnostics.

Details of BT's performance thresholds, along with troubleshooting advice, can be found here

Historical Data

Date of Report
Exchange Status
Date of Upgrade
22nd January 2007
RED
07/02/2007
8th January 2007
RED
07/02/2007
1st January 2007
RED
07/01/2007
18th December 2006
RED
07/01/2007
18th December 2006
RED
07/01/2007"

According to [tbb removed staff name] of the Zen tech support team, the roll out of maxDSL and up to 8mb broadband connections this contention problem is effecting the vast majority of exchanges across the UK.

Anyone else experiencing this? It's tempting me towards cable broadband (Telewest in our area - although I don't get a warm fuzzy feeling of confidence about them), which is a real shame for Zen, as I've otherwise been extremely pleased with my service so far (I migrated from E7, you couldn't get much worse!)

Unfortunately, they haven't yet unbundled my local exchange so I can't get MaxADSL

What exactly does this "upgrade" at the exchange entail? My connection only started to get slow about mid-November. It's really frustrating because my Home 2000 service is now working at about Home 500 levels. And no, I'm not daft enough to expect a 2 megabit line to always perform at 2 megabit, but to drop to barely 3 times dial-up is taking the proverbial.

Edited by MrSaffron (Fri 09-Feb-07 15:06:44)

The upgrade usually involves the fitting of equipment called a DSLAM, which is what interfaces customers to the back-haul to the ISP. As the numbers of ADSL customers increases, then extra DSLAMs have to be installed to handle the capacity.

Take a look at this it will explain the workings of ADSL and the jargon used.

Zen can't do much other than wait for BT to complete the work, because BT own and operate the equipment. On the positive side, BT do usually complete the work on the planned dates.

Looking at the newly launched Virgin (now its merged with NTL) services I'd snap their hand off if there was cable around here, value for money is what it is, something the UK ADSL market is very much lacking in.

I, too, am interested in hearing other peoples experience of "exchange contention". My exchange is a relatively small exchange (Littleborough). It has more or less permanently showed red since before i migrated into Zen October 2006.
However, my speeds and and performance do not appear to have been affected by this. My throughput is consistently around 4600 with an IP profile of 5000, syncing around 5800. There is only marginal variation between peak / off peak.
I do understand an exchange will be marked red even though only partially congested

Would be interested in others real world experience of being on a red exchange
Tommy

They generally only need to install a new DSLAM if they are running out of free ports. You can increase the backhaul capacity without installing a new DSLAM.

Havine more subscribers than you have capacity for (needing a new DSLAM) and having your subscribers use too much bandwidth (needing additional backhaul) aren't the same thing.

I'm rapidly losing interest in running speed checkers but my experience on the Feltham exchange is that in peak hours, e.g. evening & weekend, download speeds rarely get above 500-600kbps. Upload speeds remain pretty consistent at 200 to 240kbps.

Lowest downloads I've seen were 165 and 235kbps and below the acceptable threshold of 400kbps at around 300 to 350kbps plenty of times.

Off peak, say after 12:30 to 01:00, speeds are close to 2mbps.

Bear in mind I'm on regular ADSL and not LLU. For a while, ours was the only visible wireless LAN in the road, but now there are at least 2 others. Distance from the exchange is perhaps 250 metres.

In doing the speed tests, I took care to ensure all other variables were eliminated and the results were truly comparative.

I know how you feel. Exchange contention has been getting worse and worse in my area thanks to more and more people going over to Broadband and MaxDSL. I have had a fault on my line and interleaving has been switched on by BT, but my IP Profile appears to be stuck and I think I'll have to give Zen a buzz again! No cable or LLU in these parts, btw. I'm syncing at 8128/448, yet look at the following speeds!

Date 09/02/07 17:46:30
Speed Down 1364.69 Kbps ( 1.3 Mbps )
Speed Up 373.05 Kbps ( 0.4 Mbps )

EDIT. Just checked and my exchange is green!

Edited by deleted (Fri 09-Feb-07 18:05:58)

Jeez, how many more fences are you going to look over for green grass ? I'm sure if you talk to NTL/Telewest customers, they will tell you it's no picnic.

Oh for the good old days! Back in January 2003, I was a customer of what was then BT Openworld. I was still on the 512 kbps service. When my speeds began to drop to 150 kbps, BTO logged a fault with BT Wholesale almost immediately, accepting my word that I had tested from the master socket, tried different filters, modems, etc. Both BTO and BTW staff kept in touch until the problem was sorted out.

If Zen cannot (or will not) push BTW into investigating your long-term issue (which might not be down to a congested VP at the exchange), a move to cable might be a good prospect. Alternately, if there are other reputable ISPs out there that can offer fixed rated 2 mbps connection with a monthly contract, migration could be a safe option. Another ISP might push just that bit harder than Zen. If they can

My exchange has been marked RED for all but three or four weeks since 18 September. For most of that time, I

The BT speed test is available again now. I don't think you can blame Zen for BT's shortcomings - it's BT's kit, and they don't allow anyone else to touch it.

If you think that contention is a problem that only affects ADSL, I suggest you wander over to the NTL forums - cable seems to be "the luck of the draw" too. I think you've got more chance of getting your BT contention sorted out than you have with NTL.

You're right. It's back

http://217.32.105.42/cgi-bin/home.page.pl

But only since yesterday. It's been coming and going for weeks....like the smile on a Cheshire cat.

Perhaps BT contention issues are relatively easy to solve but who's to know whether the OP's problem is to do with his RED VP or something completely different? There does not appear to have been any investigation just an easy assumpion that it's congestion at the exchange. I don't relish the prospect of NTL but if I were in his boat I take the risk.

In reply to:

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For several weeks, users have been without the BT tool that enabled them to distinguish between BT and ISP network speed-related issues

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Is there such a thing for MaxDSL users now? If I understand the updated FAQ correctly (which is a big if!) the MaxDSL version doesn't bypass your ISP.

It comes and goes:

http://bbs.adslguide.org.uk/showthreaded.php?Cat=&Board=zen&Number=2892970&page=0&view=collapsed&sb=5&o=

In reply to:

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It comes and goes:

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<g> Indeed! The FAQ I was thinking of is this , which is why I haven't tried the separate login yet (as I thought it would not tell me anthing new).

In theory you can try using the IP address, but it is not the documented way of doing things

Given obvious load issues on the testers directing people around the balancing/logging side of things doesn't help

Thanks Andrew. Perhaps I'll give it a go the next time I can't sleep!

I can't sleep lol, so I just did this BT speedtest and I'm back to 'normal' values for me.

Test1 comprises of Best Effort Test: -provides background information.
IP profile for your line is - 7150 kbps
DSL connection rate: 448 kbps(UP-STREAM) 8128 kbps(DOWN-STREAM)
Actual IP throughput achieved during the test was - 6452 kbps

My IP Profile was stuck on 6000kbps (sync 8128/448). I rang Zen and they did something to my line because my IP profile began increasing. It is now 7150kbps.

Speeds are still rubbish (1 to 2 megs) during the late afternoon and evening, but there seems to be no way round that. Just too many people using their connection at the same time!

>>Speeds are still rubbish (1 to 2 megs) during the late afternoon and evening, but there seems to be no way round that. Just too many people using their connection at the same time!

I find that too...

same here, 7000k profile @ 7968 sync, BT Speedtester is fine( 6400KBit) , VP is fine / green

but speeds are between 300K-3MBit with Zen

just ran a speedtest here :

http://www.thinkbroadband.com/speedtest/results/id/117120287322798428703.html

awful

ping to www.bbc.co.uk :

Ping statistics for 212.58.224.116:
Packets: Sent = 152, Received = 129, Lost = 23 (15% loss),
Approximate round trip times in milli-seconds:
Minimum = 44ms, Maximum = 79ms, Average = 53ms

ping to Google

Ping statistics for 216.239.59.147:
Packets: Sent = 35, Received = 27, Lost = 8 (22% loss),
Approximate round trip times in milli-seconds:
Minimum = 56ms, Maximum = 86ms, Average = 70ms

a lot of packet loss, no other downloads/uploads here (23/7 idle LOL), and high pings (ok, interleaved is on, but anyway high)

UNUSABLE for VoIP, gaming and my MS Exchange Server / Windows Mobile 5 push (15% of inbound mails will be rejected due to a connection drop, ok ... they might arrive at a later point)

besides that, Zen seems to have a network configuration problem, my router is hit every ~1h on the WAN port from IP 172.16.1.2, this is a private IP (similar to 192.168.x.x, most likely used by CISCO routers)

FIREWALL icmp check (1 of 1): Protocol: ICMP Src ip: 172.16.1.2

OK, it's only ICMP .. so I don't bother...

Well, maybe it's time for Zen to introduce traffic management or QoS/shaping ...

Whoa, I'd say the last thing we want is traffic shaping in any way shape or form.

I've no idea what's causing your problems but I'm on a "red" exchange and these are my pings to the beeb. My latest speedtest is 4.8.


Ping statistics for 212.58.224.131:
Packets: Sent = 32, Received = 32, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 24ms, Maximum = 30ms, Average = 24ms

In reply to:

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besides that, Zen seems to have a network configuration problem, my router is hit every ~1h on the WAN port from IP 172.16.1.2, this is a private IP (similar to 192.168.x.x, most likely used by CISCO routers)

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Probably more likely someone is sending out ICMP traffic with forged source IPs.

I was also thinking about spoofed IP, but shouldn't Zen's network discard unroutable private IP's ?

Unroutable yes, but think about it - the destination IP - the one that Zen's network needs to do something with in sending the traffic to you - is valid. Only the source IP - the one your equipment is supposed to respond to - is invalid. That said, it should be possible to setup something that stopped any traffic coming in with an RFC1918 IP as the source (the Zen network should by default prevent anything routing out).

I'm a bit puzzled by the log entries you're seeing, it's the sort of thing someone would do in a DoS attack, but the fact that you're only seeing one every hour or so hardly suggests it is a DoS attack. I suspect it's actually another Zen customer who hasn't setup their router properly, whose "correct" IP is close to your own. Or, it may be that your own router is seeing traffic from within your network. It wouldn't be the first time that someone had posted logs only to find that the traffic was originating from within.