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Standard User ARD
(knowledge is power) Mon 16-Sep-13 16:57:43
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Loss of throughput on ADSL2+


[link to this post]
 
I知 currently troubleshooting a few problems, the chief one being slow throughput.

I知 on an ADSL 2+ line. I知 less that 1 kilometre from the BT exchange. My downstream attenuation is 23 dB. I知 synched at 16555 kbps. My synch has been higher but this rate is the norm for the Technicolor router that I知 using to troubleshoot. As the crow flies, I知 less that 1 kilometre from the BT exchange. My downstream attenuation is 23 dB.

Until I used the Technicolor router I could count on download speeds that were consistent with my profile. Now, they池e anything between 14.5 mbps and 8 mbps. I test using the BTW site and Namesco and actual file downloads and the issue is the same. Here痴 my last result from BT:

Download speed achieved during the test was 11.99 Mbps
For your connection, the acceptable range of speeds is 4 Mbps-21 Mbps.
IP Profile for your line is - 14.69 Mbps

I contacted my ISP today about this issue, wondering whether the errors in the router log are having an impact on speed. I quote the log figures below. The ISP agent checked things out and said that according to the BT ADSL2+ availability checker 8 mbps would be the norm for my line. I致e checked it myself and it痴 true despite my distance from the exchange, attenuation of 23 dB and my current line rate. It doesn稚 add up to me.

Anyway, here are my stats:

Uptime: 7 days, 6:57:26
DSL Type: ITU-T G.992.5
Bandwidth (Up/Down) [kbps/kbps]: 1.088 / 16.655
Data Transferred (Sent/Received) [MB/GB]: 865,32 / 3,53
Output Power (Up/Down) [dBm]: 12,1 / 20,8
Line Attenuation (Up/Down) [dB]: 11,5 / 23,0
SN Margin (Up/Down) [dB]: 5,9 / 6,1
System Vendor ID (Local/Remote): TMMB / ----
Chipset Vendor ID (Local/Remote): BDCM / TSTC
Loss of Framing (Local/Remote): 0 / 0
Loss of Signal (Local/Remote): 0 / 0
Loss of Power (Local/Remote): 0 / 0
Loss of Link (Remote): -
Error Seconds (Local/Remote): 2.198 / 2
FEC Errors (Up/Down): 0 / 0
CRC Errors (Up/Down): 13.255 / 2.246
HEC Errors (Up/Down): 9.688 / 9.089

Do the errors appear severe enough to reduce download speed?

I can稚 swap the Technicolor router at the moment. I was advised to jettison my ZyXEL and can稚 replace it until tomorrow.
Standard User MHC
(sensei) Mon 16-Sep-13 17:10:17
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Re: Loss of throughput on ADSL2+


[re: ARD] [link to this post]
 
The errors dont look excessively high give 7 days up time.

CRC is under 1 per minute up and one every 5 minutes down with HEC being under 1/minute bothways. So, not a perfect line but certainly not a bad error prone one either.


Attenuations are about right and speeds around what shoud be expected. There is nothing there which jumps out.


Have you checked your MTU and RWIN settings?


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

M H C


taurus excreta cerebrum vincit
Standard User ARD
(knowledge is power) Mon 16-Sep-13 17:18:08
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Re: Loss of throughput on ADSL2+


[re: MHC] [link to this post]
 
Thanks for confirming the line errors are nothing dramatic. smile That痴 a big relief. What is troubling is the lack of consistency of throughput since I put the Technicolor in the line. (I expected a lower synch than with the ZyXEL but still expected consistency.)

I haven稚 known what 8.5 mbps looks like since I致e had ADSL 2+. I doubt I致e dropped below 14 mbps.

MTU and RWIN are as they were before I changed from the ZyXEL to the Technicolor. I don稚 want to fiddle about there until I致e had the opportunity to try another router.


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Standard User XRaySpeX
(eat-sleep-adslguide) Mon 16-Sep-13 17:21:53
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Re: Loss of throughput on ADSL2+


[re: ARD] [link to this post]
 
In reply to a post by ARD:
according to the BT ADSL2+ availability checker 8 mbps would be the norm for my line. I致e checked it myself and it痴 true despite my distance from the exchange, attenuation of 23 dB and my current line rate.
What's true? The BT Availability Checker? That's only an estimate and notoriously inaccurate. On my 19-20 Meg line it thinks it should be only 13 Meg frown.

You line should be syncing at about 19 Meg.

1999: Freeserve 48K Dial-Up => 2005: Wanadoo 1 Meg BB => 2007: Orange 2 Meg BB => 2008: Orange 8 Meg LLU => 2010: Orange 16 Meg LLU => 2011: Orange 20 Meg WBC
Standard User MHC
(sensei) Mon 16-Sep-13 17:26:12
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Re: Loss of throughput on ADSL2+


[re: XRaySpeX] [link to this post]
 
In reply to a post by XRaySpeX:
In reply to a post by ARD:
according to the BT ADSL2+ availability checker 8 mbps would be the norm for my line. I致e checked it myself and it痴 true despite my distance from the exchange, attenuation of 23 dB and my current line rate.
What's true? The BT Availability Checker? That's only an estimate and notoriously inaccurate. On my 19-20 Meg line it thinks it should be only 13 Meg frown.

You line should be syncing at about 19 Meg.



He's syncing at around 16.5 which might be a little low and the SNR is around 6dB - so nothing to panic about. But a throughput as low as he is seeing suggests an issue somewhere but probably not on the line.


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

M H C


taurus excreta cerebrum vincit
Standard User ARD
(knowledge is power) Mon 16-Sep-13 17:52:41
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Re: Loss of throughput on ADSL2+


[re: XRaySpeX] [link to this post]
 
Thanks for your opinion regarding the synch I ought to reach. I've never synched that high even from the test socket. With hindsight, I think I syched at about 18.2 from the test. 17.5 is the highest from the master socet with a filtered faceplate. I was very happy when I was above 17 mbps but I don't think I'll get that on a router with the broadcom chipset. I don't mind a lower synch but when it comes with poor throughput... frown

Edited by ARD (Mon 16-Sep-13 18:32:02)

Standard User ARD
(knowledge is power) Mon 16-Sep-13 17:56:39
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Re: Loss of throughput on ADSL2+


[re: MHC] [link to this post]
 
The speed issue began when I started using the Technicolor router. Could be coincidence. Time and another router will tell.
Standard User yarwell
(sensei) Mon 16-Sep-13 19:45:51
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Re: Loss of throughput on ADSL2+


[re: ARD] [link to this post]
 
you could try getting it interleaved ? Most of those errors might be sorted by that.

A prolonged ping test or a utility like MTR or pingplotter would show if you were losing packets.

--

Phil

MaxDSL - goes as fast as it can and doesn't read the line checker first.

MaxDSL diagnostics
Standard User Apprentice
(knowledge is power) Mon 16-Sep-13 22:03:55
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Re: Loss of throughput on ADSL2+


[re: ARD] [link to this post]
 
In reply to a post by ARD:
The speed issue began when I started using the Technicolor router. Could be coincidence. Time and another router will tell.

Are you using it wired or wireless?

Alastair

omadasafisho
Standard User ARD
(knowledge is power) Tue 17-Sep-13 09:04:45
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Re: Loss of throughput on ADSL2+


[re: Apprentice] [link to this post]
 
I'm working wireless...as always. Perhaps the Technicolor doesn't give the same wireless performance as the ZyXEL?
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