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Recent Plusnet Speed Issues

mr_chris
Grafter
Posts: 25
Registered: 31-07-2007

Recent Plusnet Speed Issues

Recent Plusnet Speed Issues

There are many posts discussing the recent speed and latency issues that some Plusnet customers are experiencing.

While these are ongoing, I have attempted to consolidate and explain the information below, which should hopefully answer a few questions.


Background
Plusnet, like all ISPs, have a number of BT Central Pipes. These are the final part of the journey from your home to your ISP, and all traffic from every Plusnet ADSL user is carried through these central pipes (often abbreviated to "BT centrals", or "Centrals" or just "pipes").

These central pipes come in different bandwidth options, to cater for ISPs of different sizes. The most common sizes are 34Mbps, 155Mbps and 622Mbps. Plusnet have 10 x 155Mbps and 2 x 622Mbps centrals. To ease the cost to the ISP, 622Mbps centrals can be activated in segments of 155Mbps over the course of the first year. At the time of writing, Plusnet have 3 x 155Mbps segments activated on the first pipe and 1 x 155Mbps segment activated on the second pipe.

Under BT's standard charging, ISPs could afford to keep a significant amount of bandwidth spare in their central pipes. Some keep to as little as 50% capacity in order to provide more than enough bandwidth in the event of one or two (or more) centrals being out of service, or a significant event that attracts an unusually large demand for bandwidth.

Capacity-based charging, or CBC, is different. The upside is that due to reduced monthly subscription costs per user, an ISP can provide higher bandwidth products at much lower prices. The downside is that a 622Mbps central pipe on CBC costs over 1.75 million a year to rent, compared to 205,000 on standard charging. This means that if an ISP wants to stay competitive price-wise, they have to run the central pipes near capacity, and could not afford the spare bandwidth they could enjoy on standard charging.

However, Plusnet do still keep some spare capacity. If you look at Plusnet's Bandwidth Utilisation graphs, this shows that they are not exceeding available capacity. To put it into perspective, although it may look a little bit "full", there is over 150Mbps of spare bandwidth at peak times; this is more than some ISPs run their whole business on!


So what exactly is the problem?
Due to the mixture of 155Mbps and 622Mbps centrals in use by Plusnet, It has come to light that there is a fault with BT assigning users to pipes at logon. This is called load-balancing, and should work by equally distributing users between the various centrals belonging to an ISP, so as not to overload any one pipe. There appears to be a flaw in the BT system, which is causing some of the 155Mbps pipes to become overloaded at peak times. This will show itself as slightly reduced speeds, and high/erratic ping times.

Approximately 1 in 28 users will be affected, according to Plusnet.


Why isn't this affecting any other ISP?
Simply because Plusnet are the first ISP to be in this situation. They have over 70,000 ADSL subscribers and a unique mixture of different bandwidth central pipes. It could easily have been another ISP, but it just happens to be Plusnet being affected at this stage.


How can I tell if I'm affected?
Plusnet's centrals terminate in 2 different locations. the 10 x 155Mbps pipes terminate in Telehouse East. Here there are two Redback SMS10000 aggregators, known as the "Redbacks". 5 central pipes connect into each of the Redbacks.

At Telehouse North, this is where the 2 x 622Mbps central pipes come in. They each connect into a Juniper ERX-1440, known as the "Junipers".


If you think you're being affected by slow speeds and/or latency, you can run a traceroute to any website such as adslguide.org.uk. Detailed instructions for running a traceroute in Windows can be found here.

If your first hop (or second hop if you use a router) has pth-ag1 or pth-ag2 anywhere in it, e.g:

  • lo0.plusnet.pth-ag1.plus.net [195.166.128.11]
  • lo1.plusnet.pth-ag2.plus.net [195.166.128.6]

then you are connected to a Redback, and are going through a possibly congested 155Mbps central pipe.
Note pth-ag1 and pth-ag2 means plusnet telehouse east, and aggregators 1 and 2 respectively. (lo0 and lo1 are loopback interface 0 and 1, if you were wondering)


What can I do about it?

You can either wait for BT to come up with a solution, or try and reconnect in order to get onto an uncongested pipe.

If you disconnect (or just log off) and log back on again, you will likely be allocated to a different pipe. You can keep disconnecting/reconnecting and running a traceroute until you find yourself connected to a pipe that isn't suffering from bad latency. For reference, the Junipers (where the 622Mbps pipes terminate) will show themselves in a traceroute as ptn-ag1 or ptn-ag2 (note the n meaning Telehouse North):

  • lo0-plusnet.ptn-ag1.plus.net [195.166.128.123]
  • lo0.plusnet.ptn-ag2.plus.net [195.166.128.53]

If you find yourself on one of these gateways, then things should be a lot more stable. Be warned that it may take a number of attempts before you get onto a 622Mbps pipe (there's roughly a 6 in 28 chance of doing so).

__________________

Rest assured that both Plusnet and BT are fully aware of the problem, and are working closely together to try and find a solution, which will benefit all ISPs in the long term.

Hopefully this has answered a few questions about the problems that people may have been thinking of asking.

[Moderators Note by Colin(csogilvie): Post stickied]
29 REPLIES
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slow

Traceroute Results: View Traceroute
Traceroute Time (24 Hour): 22:05 to 16:13
Traceroute Duration: -352 minutes
Traceroute Packet Size: ? bytes
Exchange: woodley
Problem: Permanently Slow Data Transfer (Everything is slow)
Duration of Problem: Less than 1 week
Minimum Speed Achieved On PlusNet Speedtest: 894.8 kbps
Maximum Speed Achieved On PlusNet Speedtest: 1920.8 kbps
Average Speed Achieved On PlusNet Speedtest: 1407.8 kbps
Account: ADSL Home (Self Install) - 2mb (50:1)
IP Block Size: Single (default)
Ticket Number: None
Additional Information: None
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Recent Plusnet Speed Issues

Re-connecting does indeed eventually get you on the 'fast route'

Unfort - after doing this the connection is invariably lost and re-connected every 24 hours or so - pushing me back on the pth 'slowbies';


Surely theres another fix in the pipeline for this issue?
Possibly some work to change the 6 in 28 odds to something ideally like 'everyone on the fast side' possibly just getting closer to evens though?
keithcalder
Grafter
Posts: 182
Registered: 03-08-2007

Recent Plusnet Speed Issues

\yep, noticed the same thing here, get connected to ptn and get disconnected from them, router automatically reconnects but usually onto a congested pipe. But its bearable, seeing a simple disconnect/reconnect usually fixes things. It will be solved in time, hopefully not to far in the future and Plusnet cannot be held at fault anyways.
flicker
Grafter
Posts: 223
Registered: 31-07-2007

Recent Plusnet Speed Issues

I'm getting fed up with it now to be honest. I have just disconnected and re-connected six times, and am still on a go-slow - Connection Speed 0. The only time I get a fast "pipe" is if I connect up in the afternoon of a weekday and leave it connected till I go to bed. Never get a good one in the evening. Forum pages are loading at about the same speed as when I was on dial-up and was connected at 43.00bps Cry
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Recent Plusnet Speed Issues

but have you run a speed test?

Forums pages can sometimes be slow to load, it doesn't always mean your connection is slow.
flicker
Grafter
Posts: 223
Registered: 31-07-2007

Recent Plusnet Speed Issues

Er, like this you mean?

0 kbps YOU
53.3 kbps 56k Dial Up
64 kbps ISDN 1 Channel
128 kbps ISDN Dual Channel
460 kbps ADSL 500
920 kbps ADSL 1000
1840 kbps ADSL 2000


The following table shows the speeds you achieved from previous runs of the speed tester:

Date Speed Achieved (kbps)
24-10-2004 18:57:53 0
24-10-2004 18:46:10 0
24-10-2004 18:44:26 0

Like I said, the only time I can get a fast connection is during the daytime - eg:
22-10-2004 14:34:08 1387.2

Is it just a coincidence or is it that there are just so many more people trying to connect in the evening I wonder? Out of 20 times I have run the speed test, 13 of them I have a speed of 0. The remaining 7 times when I have had a fast connection, three of those have been in the afternoon,only four times in an evening have I a speed which is acceptable.
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Recent Plusnet Speed Issues

A speed reading of zero, doesn't mean your connection as at fault, it just means the speed checker hasn't worked correctly. Download Netstat from the analogx site and let that run on your machine.

This program displays graphes, and values for your current upload and download speed, in addition it displays your current, average and max speeds for both upload and download.


Aaron
flicker
Grafter
Posts: 223
Registered: 31-07-2007

Recent Plusnet Speed Issues

Thanks for the reply again. I have now done as you suggest and downloaded Netstat. I have the little box on display but I'm afraid the figures its showing dont mean a lot to me! So I am none the wiser. :?

It says Incoming Current OB Average OB Max 66.2KB
Outgoing Current OB Average OB Max 16.8KB

CPU (whatever that is) is fluctuating between Current 1% to 7% Average 4%
Max 99%

I'm sure this means something to somebody, but not to me!
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Recent Plusnet Speed Issues

You need to go into the configuration and change the options to display the information in bytes rather than Kilobytes( Hard disk settings), this will ensure the values match those on the speed checker within Plus Net.

The values will only change, as you use your connection, they are a reflection of your speed as it's been used. In addition the graph will show you how your speed pans out. Try downloading a file from the file vault and watch the figures and that will give you an indication of how your connection is performing.

Aaron
flicker
Grafter
Posts: 223
Registered: 31-07-2007

Recent Plusnet Speed Issues

Thanks again for the speedy reply. I'm not sure how to go about getting to the configuration though - sorry, not all that hot on the technicalities. Shockedops:

Maybe I should just give in gracefully and be grateful for the fact that I can get online at all.
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Recent Plusnet Speed Issues

You just right click on the window and select configuration. You also have the option to reset the stats and decide what stats are displayed.

Aaron
flicker
Grafter
Posts: 223
Registered: 31-07-2007

Recent Plusnet Speed Issues

Thank you so much for your help. I have done as you said, and have just downloaded a file from the vault. I now have a motorcross game to play with! (I am getting good at this Wink ) Okay, so the reading from Net Stat gave me an average download speed of 994 Kb, the 41MB file took about 6 minutes to download, which is great. I just checked on the PlusNet speed checker, and of course, it is afternoon again, and is showing my connection speed at 1018 kbps. I will try something else again later tonight, when no doubt it will be back to the usual O! Thanks again, at least I know the right way of going about checking now Smiley
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Recent Plusnet Speed Issues

If you leave the Netstats program running, and don't shut it down before powering off etc. It will actually help you to keep an eye on how much your downloading and upload. Add the two together and you've got a fairly close guide to your usage.

Aaron

Ps, you can also set the program to start automatically on boot with windows and to start minimised.
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just curious...

lo1-plusnet.ptn-ag2.plus.net

I'm sure I've read on the forums, that plus.net realm users could not get onto Juniper.... have I missed something?? or am I just having a numpty moment? if so.... I blame it on my day at work today Cheesy