Fast DSL connection but poor throughput.

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stevenz

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Topic # 87785 7-Aug-2011 09:46

I've got a 15Mbps DSL connection but can't get anything better than about 4.5Mbps throughput. I've tried different cables but that hasn't helped, currently plugged directly into the modem.

It's possible the modem is on the way out, in which case, what's a good replacement? Something that can be bridged to PPPoE (so my good router can do NAT duties) would be nice but I don't fancy my chances.

Any other suggestions on things I could check? The current modem is a DSE unit which is a rebranded TP-Link TD-8840 which has been great in the past (Broadcom based).

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Reply # 502922 7-Aug-2011 10:27

When you say it only hits 4.5Mbps how are you measuring that? With a single http connection, a speed test website, or a well seeded torrent?

I find the Auckland WorldXchange speedtest.net server the fastest in NZ, in TC cable. I get much lower pings and much faster speeds from that then from the Auckland server.

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DjShadow

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Reply # 502941 7-Aug-2011 11:37

odd I found the Vodafone one in Auckland to give me a much more reliable figure

timmmay

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Reply # 502942 7-Aug-2011 11:38

It depends on what ISP you're with, and how they peer.

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johnr

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Reply # 502951 7-Aug-2011 11:55

speedtest sites are a rough guideline

muppet

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Reply # 502960 7-Aug-2011 12:22

I deal with these sorts of faults on a weekly basis at my place of employment. The major difference being the person complaining is on the end of an Ethernet connection we have shaped to a certain speed (20Mb/s for example)

Almost always, the fault is one of the following:

1) User is using Speedtest.net. It's a great tool, but it's not exactly scientific. I prefer to get people to install the DownThemAll Addon for Firefox and download a Ubuntu ISO using at least 4, if not more, concurrent sessions. This usually "fixes" the "problem" for them.

2) A number of people have Windows XP which doesn't, by default, have the TCP Sliding Window extensions enabled. The TCP Optimiser is a great tool for this: http://www.speedguide.net/downloads.php - Enabling RFC1323 (http://www.ietf.org/rfc/rfc1323.txt) using TCP Optimiser can have some good performance improvements for downloads over a long distance. It won't affect (much) speedtest tests.

3) Using a laptop running on battery power. I have no idea why, but sometimes you see a massive performance increase when you plug the laptop into mains.

4) Wifi network is poxy. For decent performance tests, please plug in the cable.

5) (Not so relevant here) - The bottleneck is in the corporate network itself, often a Firewall is misconfigured or just over stressed. If your Router is flakey it could well be the problem.

All that said, in a ISP Network Line Speed is no promise of actual data speeds. You might be being rate-shaped at the ISP's BRAS (unlikely), they might have congestion in their backhaul or upstream networks.

I kinda rambled a bit here. But those points are essentially things to check and let us know how you get on.

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coffeebaron

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Reply # 502975 7-Aug-2011 13:48

Also, what is your upstream speed? If you are on an old FS/128 plan, then the most you'll get is about 4.5 down.

Chorus has spent $1.4 billion on making their xDSL broadband network faster. If your still stuck on ADSL or VDSL, why not spend from $150 on a master filter install to make sure you are getting the most out of your connection?
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Talkiet

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Reply # 502978 7-Aug-2011 14:02

Try this speedtest..

http://speedtest.telecom.co.nz/

What result does that give?

Cheers - N

Talkiet

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Reply # 502980 7-Aug-2011 14:05

coffeebaron: Also, what is your upstream speed? If you are on an old FS/128 plan, then the most you'll get is about 4.5 down.

It's certainly worth checking the upstream - this should show up easily in a speedtest. BTW the 4.5mbps is an out of date figure - that hasn't been accurate since Windows XP days.

Cheers - N

MrSteel

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Reply # 503071 7-Aug-2011 19:14

I have the same problem. Over a month ago now our area got upgraded to ADSL2+ and though my router says that I'm connected to ADSL2+ now and have attainable speeds of around 18Mbps down/0.9Mbps up, I only really get about 7.6 Mbps down/0.4Mbps up using Telecom's speedtest tool.

I've spoken to Telecom's Complex Technical team twice about the issue and they couldn't figure it out. They said there was nothing that was limiting my rate profile and they even did a port reset to no avail. Am I just expecting too soon for a speed increase considering that the ADSL2+ upgrade on my area just happened recently? A friend of mine from work has told me that the whole migration could take about 3 months in total and the Telecom Wholesale ADSL2+ checker is purely indicative only. Is he right?

(NOTE: As always, I have tried different cables, filters, and several ADSL2+ modems to see if my throughput changes, but got the same results.)

stevenz

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Reply # 503263 8-Aug-2011 12:07

I get just shy of 1Mbps upstream (usually around 0.8Mbps). I've tried various Speedtest servers (including the Ookla test via Telecom's speedtest, as well as downloading large files (OS X update, Ubuntu ISO).

With the same hardware, and the same location, I was at one stage rarely hitting 2MB/sec at peak (approx 16Mbps) and consistantly getting at least 1.2MB/sec (about 10Mbps). To me that suggests either some of my hardware is having issues (using ethernet so wifi isn't the problem), or there's an issue with the phone system or ADSL. I find it doubtful that I'd be the only one on the exchange with this problem if there was one so that'd be pretty unlikely I'd have thought.

I haven't tried a different DSL filter, might be worth a shot but I would've figured issues with that would show in the connect speed?

Looks like the cheap Draytek 120 modem supports a pure bridged mode which I can hook into my 532Mhz Asus RT-16N router to handle things, will see if I can pick one of those up and see if it helps matters.

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Talkiet

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Reply # 503276 8-Aug-2011 12:29

stevenz: I get just shy of 1Mbps upstream (usually around 0.8Mbps). I've tried various Speedtest servers (including the Ookla test via Telecom's speedtest, as well as downloading large files (OS X update, Ubuntu ISO).

With the same hardware, and the same location, I was at one stage rarely hitting 2MB/sec at peak (approx 16Mbps) and consistantly getting at least 1.2MB/sec (about 10Mbps). To me that suggests either some of my hardware is having issues (using ethernet so wifi isn't the problem), or there's an issue with the phone system or ADSL. I find it doubtful that I'd be the only one on the exchange with this problem if there was one so that'd be pretty unlikely I'd have thought.

I haven't tried a different DSL filter, might be worth a shot but I would've figured issues with that would show in the connect speed?

Looks like the cheap Draytek 120 modem supports a pure bridged mode which I can hook into my 532Mhz Asus RT-16N router to handle things, will see if I can pick one of those up and see if it helps matters.

Hmm, so what speed are you getting off the telecom speedtest server now (or any really offpeak time - ie not between 4pm and midnight)? The reason I ask is that if you can't get more than 4.5mbit 24*7 then it's likely to be a different issue than if you only achieve those speeds during busy times.

Can you run a speedtest on the Telecom speedtest server right now?

Cheers _ N

Talkiet

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Reply # 503279 8-Aug-2011 12:30

Also, please post your full connection stats so we can see if interleaving is on, noise margins and FEC errors (if interleaving is on) etc.

Cheers - N

stevenz

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Reply # 503288 8-Aug-2011 12:43

Sorry, at work at the moment, best "off-peak" I could manage would be early in the morning probably. I'll check it out when I get home and send it through.

When I last checked the Telecom speedtest it was about 9am Sunday morning, I was only getting around 4Mbps.

FWIW - I'm about 50m from a cabinet as the crow flies (or, what I believe is a Telecom cabinet anyway) - I'll check what the line stats suggest about this though.

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timmmay

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Reply # 503290 8-Aug-2011 12:46

TCP effectively limits the speed of any individual connection, which is why I asked about your speed on a well seeded torrent. I can max out my connection on a torrent, but usually can only get 2Mbps - 4Mbps from any individual US based server.

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stevenz

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Reply # 503303 8-Aug-2011 13:18

timmmay: TCP effectively limits the speed of any individual connection, which is why I asked about your speed on a well seeded torrent. I can max out my connection on a torrent, but usually can only get 2Mbps - 4Mbps from any individual US based server.

The last torrent I tried was sitting on 250-300 Kb/sec, I don't think my modem handles torrents very well though, I think the large number of simultaneous connections is a bit much for it to handle. The awful Thomson modem I've got handles it just fine though, but the interface on it is so unbelievably slow (as in upwards 30secs to load each page versus the ~1-2 secs from the router) that I gave up with it as it was too painful to configure. I might try plugging that back in and grab an Ubuntu ISO torrent or somesuch to see how it goes.

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