The unsolvable ADSL problem

Hi all,

Does anybody have any suggestions for tracking down ADSL interference?

I have a problem which seems to always show up at night, sometimes in
the day time and almost never in the morning as far as I can tell.

Every other aspect has been checked (the ISP, the cables, the modem,
the computer, the network card, the splitter, believe me - everything)
and after 2 weeks of daily calls to the DSLAM techs at my telco I am
pretty sure they are not to blame.

What is weird is that I don't lose sync, I don't get any errors
reported by the modem and line statistics (noise level, attenuation,
etc) do not change when the problem occurs.

The exact symptoms are as follows;

A ping to my ISP's gateway (first hop) measured when the line is idle,
increases from an average of about 35ms to an average of 60-100ms.

Downloads decrease from 48k/sec (its a 384kbps line) to anywhere
between 24-38k/sec and line latency while downloading gets incredibly
high, between 1800 and 3500ms (it is around 900-1100ms under normal
conditions).

The strangest thing is that a VOIP app I use (www.mywebcalls.com)
causes the latency to continuously increase until no more data is
received, even though this app only transfers between 2-4K/sec! Under
normal conditions my average ping while using this app is about 55ms.

The problem occasionally occurs for short periods of time but usually
goes on for at least 4-5 hours.

Any ideas?

The modem is a Zyxel 650R-33 (ADSL over ISDN) connected to a Siemens
DSLAM and the symptoms are the same no matter which ISP I use.

Cheers,
-dave

In article <(E-Mail Removed) >, (E-Mail Removed)
says...
> Hi all,
>
> Does anybody have any suggestions for tracking down ADSL interference?
>
> I have a problem which seems to always show up at night, sometimes in
> the day time and almost never in the morning as far as I can tell.
>

[snip]

> Any ideas?
>
> The modem is a Zyxel 650R-33 (ADSL over ISDN) connected to a Siemens
> DSLAM and the symptoms are the same no matter which ISP I use.

I've heard P2P apps can cause problems similar to this, because all the
packets to different hosts cause the routing table to become overloaded.

Have you tried power-on resetting the router when it gets bad.

I presume you've checked your MTU settings & things.

Given your VOIP app causes problems, are its network settings very different
to your standard ones?

I know these are simple questions, but it's sometimes the simple ones that
catch us out!

Pete.

--
NOTE! Email address is spamtrapped. Any email will be bounced to you
Remove the news and underscore from my address to reply by mail

Ive heard the problem brought up before but sometimes don't street-lights
cause some interference problems with adsl?

Dan

"Pete Smith" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> In article <(E-Mail Removed) >,
(E-Mail Removed)
> says...
> > Hi all,
> >
> > Does anybody have any suggestions for tracking down ADSL interference?
> >
> > I have a problem which seems to always show up at night, sometimes in
> > the day time and almost never in the morning as far as I can tell.
> >
>
> [snip]
>
> > Any ideas?
> >
> > The modem is a Zyxel 650R-33 (ADSL over ISDN) connected to a Siemens
> > DSLAM and the symptoms are the same no matter which ISP I use.
>
> I've heard P2P apps can cause problems similar to this, because all the
> packets to different hosts cause the routing table to become overloaded.
>
> Have you tried power-on resetting the router when it gets bad.
>
> I presume you've checked your MTU settings & things.
>
> Given your VOIP app causes problems, are its network settings very
different
> to your standard ones?
>
> I know these are simple questions, but it's sometimes the simple ones that
> catch us out!
>
> Pete.
>
> --
> NOTE! Email address is spamtrapped. Any email will be bounced to you
> Remove the news and underscore from my address to reply by mail

> I've heard P2P apps can cause problems similar to this, because all the
> packets to different hosts cause the routing table to become overloaded.

I don't have any installed.

> Have you tried power-on resetting the router when it gets bad.

Many many many times

> I presume you've checked your MTU settings & things.

It can't be that. For one I'm not running PPPoE but PPPoA which I
believe isn't affected by the MTU. Also it can begin part-way through
a download. If it was something like the MTU it should happen all the
time or never, depending on each host.

I have checked with a packet sniffer and see nothing unusual going on.

> Given your VOIP app causes problems, are its network settings very different
> to your standard ones?

Nothing changes in the configuration between when everything is fine
and when there is a problem.

> I know these are simple questions, but it's sometimes the simple ones that
> catch us out!

I have been hoping all along its something simple but unfortunately it
seems like it is anything but. I might even have to have the telco run
a new line

Cheers anyway,
dave

There are no street lights where I live, plus the problem happens in
the daytime when they wouldn't (or shouldn't) be turned on.

Concerning the 2 other common causes I've heard about (dimmer switches
and central heating thermostats) - I suppose it is unlikely that
anybody would be using a dimmer switch during the day and afaik the
only apartments in the building with central heating are my own and my
neighbours. Turning the heating off doesn't solve the problem.

It's seems unlikely that I'll find out whats causing the interference
unless there is a definite pattern. Perhaps somebody can suggest how I
might reduce or avoid the interference?

Would a filter on the mains cable help?

Cheers,
-dave

"Dan" <(E-Mail Removed)> wrote in message news:<40315b8c$0$7072$(E-Mail Removed)>...
> Ive heard the problem brought up before but sometimes don't street-lights
> cause some interference problems with adsl?
>
> Dan

On Tue, 17 Feb 2004 05:29:03 UTC, (E-Mail Removed) (dave) wrote:

> It can't be that. For one I'm not running PPPoE but PPPoA which I
> believe isn't affected by the MTU.

There was a BT issue with MTU which did affect PPoA - but only under
heavy BT network load. Not sure if it's fixed everywhere yet.

> Also it can begin part-way through
> a download. If it was something like the MTU it should happen all the
> time or never, depending on each host.

The above issue could happen at any time. It's related to packets, not
connections.


--
Bob Eager
begin by not using Outlook Express...

>> In article <(E-Mail Removed) >,
>> (E-Mail Removed) says...
>>> Hi all,
>>>
>>> Does anybody have any suggestions for tracking down ADSL
>>> interference?
>>>
>>> I have a problem which seems to always show up at night, sometimes
>>> in the day time and almost never in the morning as far as I can
>>> tell.
>>>
>>
>> [snip]
>>
>>> Any ideas?
>>>
>>> The modem is a Zyxel 650R-33 (ADSL over ISDN) connected to a Siemens
>>> DSLAM and the symptoms are the same no matter which ISP I use.


Whereabouts are you, geographically? Presumably not in the UK because - as
far as I know - ADSL over ISDN isn't available here!
--
Cheers,
Tim
______
Please reply to newsgroup. Reply address is Black Hole!

"Bob Eager" <(E-Mail Removed)> wrote in message news:<176uZD2KcidF-pn2-(E-Mail Removed)>...
> On Tue, 17 Feb 2004 05:29:03 UTC, (E-Mail Removed) (dave) wrote:
>
> > It can't be that. For one I'm not running PPPoE but PPPoA which I
> > believe isn't affected by the MTU.
>
> There was a BT issue with MTU which did affect PPoA - but only under
> heavy BT network load. Not sure if it's fixed everywhere yet.

Well I'm not actually on BT but it's interesting to hear that they had
such a problem. I still don't understand how it can happen though. The
MTU is either an acceptable size for the connection to a particular
host, or its not.

Could somebody who has experienced this problem with BT give some
details on the symptoms, the cause (?) and the solution so I can see
how it relates to my problem?

In the meantime I have had my telco switch me to Interleaved mode in
the hope that if the problem is related to noise, interleaving will be
enough to overcome it. Now i just have to wait....

Cheers,
-dave

In message <(E-Mail Removed) >, dave
<(E-Mail Removed)> writes
>Hi all,
>
>Does anybody have any suggestions for tracking down ADSL interference?
>
>The exact symptoms are as follows;
>
>A ping to my ISP's gateway (first hop) measured when the line is idle,
>increases from an average of about 35ms to an average of 60-100ms.
>
Your average of 35ms is very slow. It should be nearer to 16ms using a
router and in the 20's for an ADSL modem. Dial up is usually better
than 35ms.

>Downloads decrease from 48k/sec (its a 384kbps line)

A 384kbps ADSL service? Which ISP are you using?

>The modem is a Zyxel 650R-33 (ADSL over ISDN)

You can't have ADSL over ISDN - are you sure you've got ADSL?

> connected to a Siemens
>DSLAM and the symptoms are the same no matter which ISP I use.
>
If you have got ADSL you can only connect to the one ISP with whom you
contracted for the service! The only way in which you can connect to
other ISPs, on an ADSL enabled line, is to use the analogue side and
dial up using a regular modem and get a max 56k.

The presented scenario doesn't hang together for me.
--
Malcolm

On Tue, 17 Feb 2004 10:58:58 UTC, (E-Mail Removed) (dave) wrote:

> Well I'm not actually on BT but it's interesting to hear that they had
> such a problem. I still don't understand how it can happen though. The
> MTU is either an acceptable size for the connection to a particular
> host, or its not.

No, you are probably on BT (most ADSL is) even if they are not your ISP.

Yes, the MTU can affect it..the either..nit statement is incorrect. Look
back in Google Groups for this group, for full technical details.

--
Bob Eager
begin by not using Outlook Express...