Can you post up the complete statistics from your router? Including error counts such as CRC, FEC, HEC etc.

Can you also see what MTU is configured on your router?

Edited by deleted (Sat 16-Apr-11 16:20:44)

Hi GeeTee,

Here�s the data. I can see how it explains the DSL sync drops, though here have been none so far today, but not this new problem. I�ve just updated my browser. A 7.3 MB file download at 66 KB/sec.

Chantype: Interleave

DSL standard: ADSL2PLUS
UpstreamRate: 1152 kbps
DownstreamRate: 15992 kbps
Upstream Attainable Rate: 22675 kbps
Downstream Attainable Rate: 15272 kbps
noise margin upstream: 5 db
output power downstream: 20 db
attenuation upstream: 5 db
noise margin downstream: 4 db
output power upstream: 0 db
attenuation downstream: 23 db
Up/Down stream FEC : 0/ 6496924
Up/Down stream CRC : 52726/ 165244
Up/Down stream HEC : 1317183/ 261922
Up/Down stream ES : 19383/ 8295
Up/Down stream SES : 19383/ 2982
Up/Down stream UAS : 29/ 30
Up/Down stream LOSS : 0/ 5241872
Up/Down stream NCD : 0/ 0
Up/Down stream LCD : 0/ 0

The MTU is set at 1500

Edited by ARD (Sat 16-Apr-11 18:23:30)

Could you post your modem uptime and model?

Strange stats with a downstream rate (15992 kbps) greater than the attainable rate (15272 kbps) and the upstream attainable rate (22675 kbps) is impossible.

The router I'm using now is a Zyxel P-660HN-F1Z.

I've just lost sync and reconnected at 15448 kbps but here's the stat that interested you again:

DSL standard: ADSL2PLUS
UpstreamRate: 1144 kbps
DownstreamRate: 15448 kbps
Upstream Attainable Rate: 22478 kbps
Downstream Attainable Rate: 15364 kbps

Edited by ARD (Sat 16-Apr-11 18:06:08)

How long had the connection been up at that point?

It would be interesting to take a snapshot of the error counts, run some large downloads for 5 minutes or so, then take another snapshot. That way we would have a good idea how badly the line is being effected.

The FECs are data packets that have been damaged in transit but been salvaged successfully thanks to the interleaving. This saves them having to be retransmitted but dependant on the processor in the router may have a negative impact on throughput if it has to repair a lot in a short time.

9-10 hours.

However, the line condition is the same when I run the BT Speed Test. The stats don't explain the difference between a BT result in keeping with a 13000 kbps IP Profile and the speeds I'm getting elsewhere. I've just tested from my own ISP website. Result? 1.5 mbps.

Edited by ARD (Sun 17-Apr-11 08:23:11)

Does the connection still drop sometimes when you receive phone calls?

The disconnections have never been due exclusively to phone use, though they were most commmon when using the phone. For example, on Friday I lost sync during a phone call and again when the phone was not in use. Yesterday, phone calls did not cause disconnections but there was a drop with nothing to do with phones. I've just made a call and there was no sync loss. Part of the problem has been the absense of a pattern.

At the moment , though, my main concern is the strange speed issue. Here are today's BT results:

Download speedachieved during the test was - 10626 Kbps
For your connection, the acceptable range of speedsis 4000-21000 Kbps.
Additional Information:
Your DSL Connection Rate :15640 Kbps(DOWN-STREAM), 1144 Kbps(UP-STREAM)
IP Profile for your line is - 13000 Kbps
The throughput of Best Efforts (BE) classes achieved during the test is - 17.94:25.7:56.36 (SBE:NBE:PBE)
These figures represent the ratio while sententiously passing Sub BE, Normal BE and Priority BE marked traffic

Download speedachieved during the test was - 11149 Kbps
For your connection, the acceptable range of speedsis 4000-21000 Kbps.
Additional Information:
Your DSL Connection Rate :15672 Kbps(DOWN-STREAM), 1152 Kbps(UP-STREAM)
IP Profile for your line is - 13000 Kbps
The throughput of Best Efforts (BE) classes achieved during the test is - 18.76:21.25:60.0 (SBE:NBE:PBE)
These figures represent the ratio while sententiously passing Sub BE, Normal BE and Priority BE marked traffic.

Elsewhere, my downloads have been 2.6-1.5 mbps.

Edited by ARD (Sun 17-Apr-11 14:08:20)

The dropping connections and errors indicate a problem on the copper line. This should be resolvable by a thorough Openreach SFI engineer.

The throughput difference between the BT Speedtest and every other download / speedtest indicate congestion or peering issues with your ISP.

Unfortunately this is all in the hands of your ISP to fix

As Andrew pointed out at the beginning, there are at least two ISPs who hold copies of the IP Profile within their system.

This copy is what is used to control your speed, not the IP Profile itself.

The copy is supposed to be automatically updated by a feed from BT when it changes. This auto system frequently fails. So if it was at 4000kbps or lower, and if the ISP also has BT speed tests routed to bypass their internal systems - which some do, then you would get exactly the effect you are observing.

AAISP are is one and Plusnet is the other. I don't know about AAISP, but certainly at Plusnet first-line support when asked what the profile is will look at the BT reading that they can see for your line, not their internal copy. They seem unaware that the copy even exists.

On Plusnet you can see what the internal copy is by going into your control panel and finding the "Current Line Rate". If it is AAISP I don't know. If it is some other ISP then, once again, you know what we need to know.