Very poor line synch after getting a Billion 7401VGP

Modem setup, reviews and questions (All brands, including wireless modems)
Post Reply
DaXiuyi
Posts: 15
Joined: Thu Feb 22, 2007 8:10 pm
Location: Sydney

Very poor line synch after getting a Billion 7401VGP

Post by DaXiuyi » Sat Feb 16, 2008 10:49 am

G'day everyone,

Have just upgraded my Netgear DG834 v3 to a Billion 7401VGP, and while I have a connection ok, I am worried about whether I have set everything up ok as my line synch is ~4043100. As I'm assuming this is in bytes/sec, this seems extremely slow for my ADSL2+ service given that I leave within spitting distance of my exchange (Edgecliff, NSW) and my line synch on my old Netgear was ~18000 kbytes/sec.

Have tried an isolation test with no success. My phone runs off a separate wall socket and it has an ACS ADSL2+ filter on it. Thus the phone line for the modem runs straight into the "ADSL" socket at the back of the modem. While everything seems to work ok, is this correct?

Could someone please let me know the correct settings I should have for this modem, as while I think I have set everything up ok (I simply followed the Exewiki entry for my modem), I am not familiar with the Billion interface and could easily have stuffed something up. Btw, while I do intend to be using this for wireless use for my mum's laptop, at the moment I am using it just for my PC with the ethernet cable plugged in.

Have included pings and tracerts below:

Code: Select all

C:\Documents and Settings\xxx>ping 220.233.0.50

Pinging 220.233.0.50 with 32 bytes of data:

Reply from 220.233.0.50: bytes=32 time=260ms TTL=60
Reply from 220.233.0.50: bytes=32 time=36ms TTL=60
Reply from 220.233.0.50: bytes=32 time=103ms TTL=60
Request timed out.

Ping statistics for 220.233.0.50:
Packets: Sent = 4, Received = 3, Lost = 1 (25% loss),
Approximate round trip times in milli-seconds:
Minimum = 36ms, Maximum = 260ms, Average = 133ms

C:\Documents and Settings\xxx>tracert www.telstra.com

Tracing route to www.telstra.com [144.135.19.10]
over a maximum of 30 hops:

1 1 ms <1 ms <1 ms 192.168.1.254
2 375 ms 270 ms 74 ms 150.1.233.220.exetel.com.au [220.233.1.150]
3 38 ms 35 ms 57 ms 241.0.233.220.exetel.com.au [220.233.0.241]
4 275 ms 503 ms 501 ms 10.0.1.1
5 * 220 ms 36 ms 38.2.233.220.exetel.com.au [220.233.2.38]
6 78 ms 40 ms 40 ms 359-ge-0-0-0.GW5.SYD2.ALTER.NET [203.166.92.57]

7 282 ms 220 ms 38 ms 0.so-6-2-0.XT1.SYD2.ALTER.NET [210.80.38.221]
8 * 36 ms 39 ms so-6-0-0.BR2.SYD2.ALTER.NET [210.80.33.218]
9 37 ms 40 ms 42 ms FastEthernet2-2.ken17.Sydney.telstra.net [139.13
0.4.185]
10 93 ms 74 ms 39 ms TenGigabitEthernet8-1.pit1.Sydney.telstra.net [2
03.50.20.39]
11 36 ms 39 ms 40 ms pitt-tcom-r01 [139.130.185.254]
12 203 ms 188 ms 38 ms 144.135.19.84
13 65 ms 35 ms 49 ms 144.135.19.10

Trace complete.
Here is a speed test done last night:

Code: Select all

[*Test Results from <a href="http://www.ozspeedtest.com">Oz Broadband Speed Test</a>*]`]
[(----------------------------------
Test run on [*16/02/2008*] @ [*01:59 AM*]

Mirror: [*Exetel*]
Data: [*9 MB*]
Test Time: [*87.84 secs*]

Your line speed is [*860 kbps*] (0.86 Mbps).
Your download speed is [*108 KB/s*] (0.11 MB/s). )]
While I have raised a ticket for this (#644051), I realise I should have come here to pose the question first. For that I apologise.

Any assistance with this matter would be greatly appreciated.

DaXiuyi
Posts: 15
Joined: Thu Feb 22, 2007 8:10 pm
Location: Sydney

Post by DaXiuyi » Sat Feb 16, 2008 12:56 pm

UPDATE:

Have had a port reset done (many thanks for that), and that has improved my line synch dramatically (~14000000 bytes/sec). However my download speeds are still quite poor:

Code: Select all

[`[*Test Results from <a href="http://www.ozspeedtest.com">Oz Broadband Speed Test</a>*]`]
[(----------------------------------
Test run on [*16/02/2008*] @ [*12:45 PM*]

Mirror: [*Exetel*]
Data: [*9 MB*]
Test Time: [*32.02 secs*]

Your line speed is [*2.36 Mbps*] (2361 kbps).
Your download speed is [*295 KB/s*] (0.29 MB/s). )]
I am struggling to see what settings in my modem could be wrong. Any assistance would be greatly appreciated:
Here are a few settings etc from the UI
The ADSL settings:

Code: Select all

ADSL Parameters 
Connect Mode  ADSL2+, auto-fallback 
Modulation  G.Dmt.BisPlusAuto  
Profile Type  MAIN   
Activate Line  true
Coding Gain  auto 
Tx Attenuation  Bis_0DB  
DSP Firmware Version E.67.2.37  
Connected true 
Operational Mode G.Dmt.BisPlus 
Annex Type ADSL2A 
Upstream 812900 
Downstream 16151400 
CO Vendor IFTNq 
Elapsed Time 0 day 0 hr 10 min 52 

The "ISP" tab:

Code: Select all

WAN Connection PPPoE Routed 
Description  PPPoE WAN Link
VPI  8
VCI  35
ATM Class  UBR
NAT Enable 
Username   xxxxxxxxxx@nsw.exetel.com.au
Password  ***********
Service Name Exetel  
IP Address 0.0.0.0
('0.0.0.0' means 'Obtain an IP address automatically') 
Authentication Protocol  Chap(Auto)
Connection  Always On
Idle Timeout  0 minutes
RIP  (all unchecked)
MTU  1492
TCP MSS Clamp Enable
MAC Address Spoofing Disable  
The "DNS" tab:

Code: Select all

DNS Parameters 
Obtain DNS automatically (unticked)
Primary DNS  220.233.0.4
Secondary DNS  220.233.0.3
If anyone would like more information, please let me know.

As before, any help would be greatly appreciated.

CoreyPlover
Volunteer Site Admin
Posts: 5922
Joined: Sat Nov 04, 2006 2:24 pm
Location: Melbourne, VIC

Post by CoreyPlover » Sat Feb 16, 2008 4:53 pm

Everything there seems correct. The 16Mbps/800kbps sync is good and all other parameters look normal.

Thepings and tracert results are a little flakey (i.e. they fluctuate from 36ms (normal) to 300-400ms. Maybe this is contributing to your slow speeds. Are any other downloads occurring anywhere on your network when you are performing these tests?

One thing you will find is that speeds from midnight to 3-4am will be fairly significantly impacted due to the large amount of P2P traffic that occurs during those times. Also, ozspeedtest and other web based speed meters fluctuate quite a lot (just perform some tests back to back, you may see several Mbps of speed difference). So you may wish to try a few different speedtests during afternoon hours to see what the maximum throughput of your connection is:
  • Try a few more ozspeedtests at different times, or back to back tests. Maybe throw in a few http://speedtest.net or www.exetel.com.au/speed/meter.php tests just to get a feel for the fluctuations in values that these that these tests can return. I did a few speed tests myself just then and got consistent 1.5Mbps on the Exetel meter when using an Opera browser, consistent 8Mbps on the Exetel meter when using Mozilla, then 2.5Mbps, 6Mbps, 8Mbps, and 5Mbps on successive ozspeedtest.com tests.
  • Try downloading a large file (or even better, several files simultaneously) from mirror.exetel.com.au and tallying the speeds once they stabilise. You can cancel the downloads once you have recorded speeds if you like.
  • Similarly, try finding 3-4 large files on high usage sites like microsoft.com, apple.com and download them simultaneously.

Razza
Posts: 25
Joined: Fri Feb 01, 2008 12:12 pm
Location: Sydney

Re: Very poor line synch after getting a Billion 7401VGP

Post by Razza » Thu May 22, 2008 11:37 am

I too upgraded from a Netgear dg834g to a billion. I went for a 7404vgp-m however.

I have experienced the exact same symptoms. I am synching and downloading slower with the Billion!

Below are some speed tests;
With the DG834G:
Test Results from Oz Broadband Speed Test
----------------------------------­
Test run on 21/05/2008 @ 12:06 PM

Mirror: Exetel
Data: 15 MB
Test Time: 14.8 secs

Your line speed is 8.47 Mbps (8470 kbps).
Your download speed is 1.03 MB/s (1059 KB/s).

With the 7404vgp-m
Test Results from Oz Broadband Speed Test
----------------------------------­
Test run on 21/05/2008 @ 12:13 PM

Mirror: Exetel
Data: 15 MB
Test Time: 20.83 secs

Your line speed is 6.02 Mbps (6017 kbps).
Your download speed is 752 KB/s (0.73 MB/s).

I have tested multiple times, on multiple speed testing sites with consistent results.

Has anyone had any luck with tweaking their Billion settings to achieve the values they were achieving with other modems/routers?

Is the billion slower because it is doing so much more than the netgear (QoS, ATA?) or is it just that the billion chipset is crap!

Someone on Whirlpool suggested I set my 'coding gain' under ADSL to 7 as apposed to auto. this gave me slight improvement.

CoreyPlover
Volunteer Site Admin
Posts: 5922
Joined: Sat Nov 04, 2006 2:24 pm
Location: Melbourne, VIC

Re: Very poor line synch after getting a Billion 7401VGP

Post by CoreyPlover » Thu May 22, 2008 12:24 pm

I could only suggest a firmware upgrade to the Billion to see whether there is any improvement. You can also try downgrading to previous firmware versions to check for improvement

The difference may lie in your noise margin settings on the Billion vs the Netcomm. The idea is that each modem listens to your phone line to determine a noise level and it then adds on a noise margin as a buffer and syncs at that rate. This noise margin is intended to absorb any fluctuations in line noise so that your modem doesn't have to continually renegotiate its sync. The higher the noise margin, the more stable your connection is (i.e. able to buffer higher noise fluctuations) but the lower the sync speed.

So it may be that the Billion naturally negotiates a higher noise margin than the Netcomm and in doing so trades speed for stability. The "coding gain" may be the Billion terminology for "noise margin", so by setting it lower you are regaining some speed.

Razza
Posts: 25
Joined: Fri Feb 01, 2008 12:12 pm
Location: Sydney

Re: Very poor line synch after getting a Billion 7401VGP

Post by Razza » Thu May 22, 2008 12:39 pm

CoreyPlover wrote:
So it may be that the Billion naturally negotiates a higher noise margin than the Netcomm and in doing so trades speed for stability. The "coding gain" may be the Billion terminology for "noise margin", so by setting it lower you are regaining some speed.
You have hit the nail on the head. This is what billion told me in a slightly different way. I have a SNR of 12.0dB and billion told me I should have a reliable connection on about 6.0dB.

I have just sent a support ticket requesting that my profile be increased as to take advantage of this high SNR value and increase my speed.

As far as firmware goes, I am using the latest Billion firmware.

any idea how long it might take for my request to upgrade my profile to be acted on?

CoreyPlover
Volunteer Site Admin
Posts: 5922
Joined: Sat Nov 04, 2006 2:24 pm
Location: Melbourne, VIC

Re: Very poor line synch after getting a Billion 7401VGP

Post by CoreyPlover » Thu May 22, 2008 2:27 pm

If you are currently on a reduced profile, a high noise margin would indicate that you can afford to increase it without loss of signal. However, you may already be on the highest (and standard) ADSL2+ profile. What is your current sync rate and line attenuation values?

Your modem (and its firmware) is responsible for setting the desired noise margin at 12dB (which, by the way is quite normal. Most noise margins are around 9-12dB). You sound like you have the option of decreasing this noise margin (coding gain) to 6 or 7dB via the modem's web interface. This is a local modem setting and is independent of the profile you are currently on.

If you would like to confirm your ADSL profile (and raise it if possible), perhaps try emailing residentialsupport@exetel.com.au or opening a helpdesk ticket. I would expect it will be actioned within 24 hours.

Razza
Posts: 25
Joined: Fri Feb 01, 2008 12:12 pm
Location: Sydney

Re: Very poor line synch after getting a Billion 7401VGP

Post by Razza » Thu May 22, 2008 4:34 pm

Yeah, I have experimented with coding gain. changing it to 7 as apposed to the billion default of auto had some improvement.

I have been experimenting with 7 and auto and haven't seen mucy difference.

I had a reply saying my profile had been changed (very quick turn around, less than 1 hour). After several power cycles, there was no visible change.

Interestingly, when I first power cycled the modem after being told of the profile change, I had exetel speed test give me a result of 10MBps! I was exstatic! However this has not been repeated, I am still stuck at < 7MBps.

FYI these are my connection stats from my billion:
Downstream Upstream
SNR Margin 12.0 dB 13.0 dB
Line Attenuation 25.0 dB 13.0 dB
Upstream 812900
Downstream 8201700

Your current bandwidth reading is:

6.54 Mbps

which means you can download at 836.6 KB/sec. from our servers.



Netgear Stats:
ADSL Link Downstream Upstream
Connection Speed 10391 kbps 812 kbps
Line Attenuation 25 db 6.5 db
Noise Margin 12 db 14 db

Your current bandwidth reading is:

8.30 Mbps

which means you can download at 1.04 MB/sec. from our servers.



Obvisouly the Billion is forcing itself to synch slower. As I have been told by Billion that the modem can handle a SNR of 6.0dB I really want to push the envelope and get my billion up to the estimated speeds of 11-12MBps.

I have seen no evidence of the new profile changes having taken affect.

CoreyPlover
Volunteer Site Admin
Posts: 5922
Joined: Sat Nov 04, 2006 2:24 pm
Location: Melbourne, VIC

Re: Very poor line synch after getting a Billion 7401VGP

Post by CoreyPlover » Thu May 22, 2008 11:23 pm

Razza wrote:I have seen no evidence of the new profile changes having taken affect.
I expected this would be the case.

Your line seems to have a maximum attainable sync rate of 10-11Mbps. This is determined by the distance that you are away from the exchange and the quality of your phone line. It means that regardless of whether you have a 12Mbps or a full 24Mbps (realistically 18Mbps) profile in place you will not sync higher than 10-11Mbps.

The noise margin of your line is completely determined by your modem and its firmware, not the line profile. Both modems are negotiating a 12dB noise margin and this is not be able to be changed by Exetel. Your only hope is to tweak your modem to negotiate a lower noise margin and it seems that neither of your modems allow this.

Every modem is different. Some modems are able to filter out noise better than others. Some modems are more intelligent when it comes to setting a noise margin. It means that different modems will naturally sync at different rates. There is nothing that can be done about this and besides, whether you are syncing at 8Mbps or 10Mbps, this is still more than adequate for ADSL2+.

The other important thing you should realise is not to use speed tests to judge the speed of your connection. Speed tests are subject to their own random fluctuations and the tests you have already done are indicating that you are getting high speeds anyway. Look at the line sync values on your modem to determine whether any changes are having a positive effect. Plus, you will never attain speeds equal to 100% of your line sync: there is at least 10% overhead lost during ADSL and TCP/IP transmission.

Razza
Posts: 25
Joined: Fri Feb 01, 2008 12:12 pm
Location: Sydney

Re: Very poor line synch after getting a Billion 7401VGP

Post by Razza » Fri May 23, 2008 4:08 pm

Hmmm...

Caught between a rock and a hard place. Billion says that if a faster profile is used, this will naturally produce more noise and make my SNR reduce. They say my billion should maintain a reliable connection at a SNR of 6.0dB.

Exetel is telling me it is purely my modem.

What are the profiles exetel uses? are they purely varying speeds? Are you able to tell me what pseed profile Exetel has me on at the moment?

Billion, based on my Line attenuation and SNR estimates I should achieve synchs of 11-12Mbps. ADSL2Exchanges estimates;
You are 1205 m from CRON as the crow flies.
Estimated cable length of 1867.75 m.
Estimated speed of 15000

Either way, my current synch of 8mbps is really below par! almost half of what is expected.

Based on those distances and the following modem values, what does Exetel estimate my synch speed to be?
Downstream Upstream
SNR Margin 12.0 dB 13.0 dB
Line Attenuation 24.5 dB 13.0 dB

Cheers
Ryan

ymo
Posts: 294
Joined: Sat Sep 10, 2005 4:36 pm
Location: Wollongong NSW

Re: Very poor line synch after getting a Billion 7401VGP

Post by ymo » Fri May 23, 2008 11:59 pm

Based on my experience and previous postings, Optus use a more conservative setting on their DSLAMs than other companies do. When I got ADSL2+ back in late Sept 2006 I got 17Mbps sync rates (or 8.032 with an ADSL1 modem). After one month Optus raised the SNR Margin setting on all their DSLAMs from 9dB to 12dB. My line sync fell to ~14Mbps (or 6 with an ADSL1 modem). I believe that 6dB SNR Margin is the standard setting on ADSL1 services.

This change was doubly beneficial to Optus. It makes the connections more stable and it cuts down the amount of backhaul required.

Post Reply