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Ping Test Figures with broadband fault

angiejolly
Grafter
Posts: 27
Registered: 24-02-2010

Ping Test Figures with broadband fault

I wonder if anyone can help?
I am suffering a broadband fault that has been dragging on for 12 days. The fault is still not resolved and we are now awaiting a test router form PN. We have been told that it was a network / BT equipment problem, and then that the line is fine. S/N ratio fluctuates between 4 and 8.5dB
Our connection is currently running at 192Kbps, presumably because of BT's attempts to keep the connection up.
I am so unhappy with PN's attempts to resolve the problem that I want to be able to isolate the problem myself so that the game of pass the parcel ends and we can have the fault fixed.
My hardware setup up consists of a number of Macs and iPhones connected to an Apple Airport WIFI network. The airport is then connected to a BT Voyager 205 via ethernet. The 205 is then connected into the master socket with a DECT phone on the same line. Removing the DECT phone has made no difference to performance. There has been no new equipment added to the network, or placed close to the 205.
I am running ping tests (the nearest thing I can find to BERT test) to each identifiable segment of my connection. Tests to the back of my router (192.168.1.1) are rock solid with no failed packets and response times of around 1ms. Pinging my assigned IP address 87.112.171.xxx give the same result. Pinging my default gateway IP address returns around 34ms. However, at the instant that I reload a web page (any page) ping test packets are lost and the response time shoots up to 1 to 2 seconds before falling back to 34ms. I have attached a screen shot below. When running the ping test against my assigned IP address, there is no spike in response times. At most, the response increases from 1 to 3ms.
I have two questions:
1. When I am running a ping test against my assigned IP address, how far down the connectivity path am I getting? Is this the front of the router? Is it, in effect proving my 205 is working.
2. Is there an intermediary IP address that I could ping, say at my local exchange? I cannot see anything other than 192.168.1.1 and my default gateway address when I run the trace route command against plus.net
3. What should the S/N ratio be? I was led to believe that it should be 9dB of better.
4. Would it be worth increasing the the gain of my 205, have any effect? (upping the gain via the 'modify dsl config gain' command)
DSL PARAMS
Vendor ID            : 00B5GSPN
Revision Number      : Y1921a                         
Serial number        : 123456789abcdx                 
Self Test            : Passed             
Framing Structure    : Framing-3
Standard            : G.dmt             
Trellis Coding        : Enable 
Local Tx. Power(dB)  : 12.13             
Remote Tx.Power(dB)  : 11.64   
Local Line Atten(dB) : 56.5               
Remote Line Atten(dB) : 31.5   
Local SNR Margin(dB) : 6.0               
Remote SNR Margin(dB) : 13.0   
Up SValue            : 4                 
Down SValue          : 2       
Up DValue            : 4                 
Down DValue          : 8       
          UpIntrlvd UpFast DownIntrlvd DownFast
AS0(kbps): -        -      192        0     
AS1(kbps): -        -      0          0     
LS0(kbps): 448      0      -          -     
LS1(kbps): 0        0      -          -     
RValue  : 4        0      4          0     

11 REPLIES
angiejolly
Grafter
Posts: 27
Registered: 24-02-2010

Re: Ping Test Figures with broadband fault

Update @10.32: I have just noticed that reloading this page causes the ping test response time to shoot up to around 5 seconds. I am so sick of this crappy service... Screen shot number 2 attached.
v70ben
Grafter
Posts: 119
Registered: 19-11-2009

Re: Ping Test Figures with broadband fault

Is it something as "daft" as a double NAT'ing issue... Which may well be causing issues.
Try connecting a PC (or a mac) Directly to the BT Voyager Router Ethernet port and see if you experience the same issues.
If it suddenly starts working, but then doesn't work on the Airport again, then it's probably double NAT thats the issue.
If it is Double NAT, it's because the BT Voyager will be doing NAT (Network Address Translation) and also so will your Airport WIFI which could cause issues.



angiejolly
Grafter
Posts: 27
Registered: 24-02-2010

Re: Ping Test Figures with broadband fault

Thanks, but double NAT is not the problem. I am running the Airport in Bridge mode. Nothing has changed with my WIFI settings for the last two years. The only change has been moving to PN.
dick:quote
Community Gaffer
Community Gaffer
Posts: 17,665
Thanks: 658
Fixes: 162
Registered: 05-04-2007

Re: Ping Test Figures with broadband fault

Is that IP address one of our gateways? If so you will get intermittent pings from their as that type of traffic isn't prioritised on the gateway.
You'd be better pinging something like bbc.co.uk or jolt.co.uk to get a truer reflection of latency.
If this post resolved your issue please click the 'This fixed my problem' button
 Chris Parr
 Plusnet Staff
angiejolly
Grafter
Posts: 27
Registered: 24-02-2010

Re: Ping Test Figures with broadband fault

Thanks Chris. Below is the output from a continuous ping test of bbc.co.uk. Do drop outs, but a visible increase in ping response times.
dick:quote
angiejolly
Grafter
Posts: 27
Registered: 24-02-2010

Re: Ping Test Figures with broadband fault

Quote from: Chris
Is that IP address one of our gateways? If so you will get intermittent pings from their as that type of traffic isn't prioritised on the gateway.
You'd be better pinging something like bbc.co.uk or jolt.co.uk to get a truer reflection of latency.

Here is another one. It doesn't seem right that the ping response should jump from 31ms to over 3 seconds.
Superuser
Superuser
Posts: 9,762
Thanks: 1,147
Fixes: 62
Registered: 06-04-2007

Re: Ping Test Figures with broadband fault

I'm not surprised that ping responses are much longer when the connection is flooded with TCP packets. The results you show seem quite reasonable to me.
David
Community Veteran
Posts: 1,412
Thanks: 4
Registered: 29-01-2009

Re: Ping Test Figures with broadband fault

Quote from: angiejolly
I have two questions:
1. When I am running a ping test against my assigned IP address, how far down the connectivity path am I getting? Is this the front of the router? Is it, in effect proving my 205 is working.
2. Is there an intermediary IP address that I could ping, say at my local exchange? I cannot see anything other than 192.168.1.1 and my default gateway address when I run the trace route command against plus.net
3. What should the S/N ratio be? I was led to believe that it should be 9dB of better.
4. Would it be worth increasing the the gain of my 205, have any effect? (upping the gain via the 'modify dsl config gain' command)

1. Yes, the ping to the assigned IP address is only getting as far as your router. The delays will generally give this away too.
2. No - the traceroute is already doing a systematic sequence of pings. Any intermediate equipment that doesn't get seen by the traceroute won't be visible to a manual ping either.
3. It depends on whether the BT exchange has been applying any DLM management to your line because it perceives stability issues. If not, it will target 6dB; if it has, it will target 9dB, 12 dB, or most severely, 15dB.
That targetting applies whenever the router syncs, but obviously the noise seen on the line varies continuously over time. The S/N measurements you see show this variation, and can fluctuate quite a lot - particularly dependent on ionospheric effects (dusk/dawn especially), crosstalk effects (neighbours turning broadband on) and weather.
The S/N measurement you see just after rebooting the router will generally show you what the exchange has set the target level to.
4. I don't think so. I suspect that will only increase the volume that your router shouts at the exchange with - so would only effect the uplink path.
Mike
Plusnet Customer
Using FTTC since 2011. Currently on 80/20 Unlimited Fibre Extra.
angiejolly
Grafter
Posts: 27
Registered: 24-02-2010

Re: Ping Test Figures with broadband fault

Thanks for your responses guys. The service is still shocking, but the router is holding the connection. I expect the test router to be delivered tomorrow, but I don't think it is going to make any difference.
angiejolly
Grafter
Posts: 27
Registered: 24-02-2010

Re: Ping Test Figures with broadband fault

This morning I received the test router from PN. My BT Voyager 205 had been solidly connected for some 47 hours at the time it was swapped out. Of course, installing the test unit has slowed my broadband down even more and has introduced a new symptom which is tx bandwidth being reduced from 448Kbps to 100Kbps or so. Whether it is due to BT DLM or the router being crap, I can't tell yet.
So, it looks like another another yet another 3 days of appalling service, just to prove that there is nothing wrong with my router (which there isn't).
Needless to say, I will be leaving PN the moment they fix the problem. Incompetence does not do justice to this shower...
Community Veteran
Posts: 1,412
Thanks: 4
Registered: 29-01-2009

Re: Ping Test Figures with broadband fault

Quote from: angiejolly
This morning I received the test router from PN. My BT Voyager 205 had been solidly connected for some 47 hours at the time it was swapped out. Of course, installing the test unit has slowed my broadband down even more and has introduced a new symptom which is tx bandwidth being reduced from 448Kbps to 100Kbps or so.

This isn't quite true, but it needs to be explained in a lot more detail...
For others reading this, there are details of the router stats over on this thread.
In summary, the new router has altered the behaviour of your exchange line by:
- Improving the downlink speed by making it around 9x faster (192 kbit/s to 1799 kbit/s)
- Improving the uplink speed from 448 kbit/s to 450 kbit/s.
The router has had this effect only on the line between your house and your exchange.
Unfortunately BT's DLM function has set an "IP Profile" on your line of 135 kbps, so *BT* will not allow data to travel on it's internal network (from your local exchange to PlusNet) at a rate faster than this.
When you run a speedtester (of any type), you only ever get the speed that matches the slowest component of your connection. Yesterday this was your ADSL link (between home and exchange).
Today it is BT's network, that is restricting you.
Plusnet's copy of BT's profile is set to 250, so they will stick to that as a maximum speed. I'm not sure why it is different, but PlusNet's system is *supposed* to follow BT's value.
If it doesn't then Plusnet can change their value - but only ever to set it to the same as BT.
So... you need the BT value to improve. It ought to happen automatically, so long as your new router manages to stay connected at that 1799 speed.
If you want to help it along, most people suggest that you leave the router connected 24/7, and do one power cycle per day - usually in the late morning time.
This helps the line re-synchronise at it's best, because you do it at a time of day that is usually low-interference.
Once the BT value has updated (which you see displayed when you run the BT speedtest), the Plusnet value ought to update within 24 hours (and you see this from your account login panel.
Only after all the components have been sorted will you get decent download speeds.
Keep us updated with your router statistics over the next few days, so we can see if things are going OK though...
  Mike
PS - I wouldn't worry about the FEC/HEC/CRC values either. They're not too bad.
FEC errors are ones that have been corrected, so aren't really errors.
CRC errors are the real errors. As ADSL runs at about 60 frames per second, and the connection has been up for 150 minutes, this represent 49 errors in 540,000 frames, or about 0.01%.
Plusnet Customer
Using FTTC since 2011. Currently on 80/20 Unlimited Fibre Extra.