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Re: (ASCEND) 56K modem disconnects
Have you ruled out line quality as an issue. The customers I have that have
frequent disconnects usually have a line quality problem. My first
suggestion is to upgrade the firmware on their modem, if I know it to be one
of the modem types that has historically caused problems, such as the 28.8
IBM Aptiva or older version of the 56K Motorola Modem Surfer. If that fails
then I forward some line checking suggestions I got from Ascend, as follows:
Checking Your Line Quality
If you think your noisy phone line is causing problems with your modem,
check the following:
Check the Line for Noise
First you need to get rid of the dialtone so you can really listen to the
line. Dial a number, any number but obviously one which is valid for you
area, so that you don’t get the dialtone replace by a busy signal. The
easiest and most common across all areas is a “1”. Is your dialtone gone?
Now listen and really concentrate while you are doing so because you are
only going to get 30 seconds before it times out and gets replaced by a busy
signal again.
This is the first major step to checking if you have a good line for a modem
or not. Is it quiet? No pops, bangs, crackles, creaking, or faint voices in
the background from other people’s conversations. All or any of these
noises will cause you a problem on a high speed modem link.
Just what are these noises? Well, it can be something as simple as a loose
screw on a connector block somewhere between you and the exchange, or water
getting into one of Telcos cable ducts and the waterproofing (around the
cable joints) has started to break down. You could have a bad connection in
the house somewhere, and not necessarily on the line extension that’s
feeding your modem. Other people’s conversations (called “crosstalk” in the
trade) are not so easy to pin down, and are usually more likely to be
further “into the system” before the source becomes apparent.
Check the Phone
Let’s presume you have one of these noises to some greater or lesser degree.
Next you need to check the phone itself. After all, if it’s just the phone
causing the noise, it won’t affect the quality you get from the modem now.
If you have a spare phone, it might be worth heading to the local
electronics store to pick up an inexpensive phone.
Check the Modem
Let’s assume now that you are happy with perceived “quietness” of the line.
Now you move to the modem. How can you check if you have a dodgy plug or
socket associated with the modem? Well, surprisingly, it’s reasonably simple
but you’ll need to be fairly quick in carrying out the next “test”. What
you are going to do is to get the modem to go on line, but not actually dial
out a full number (similar to what you did just now but using the modem
instead).
To do this you’ll also need to have a phone plugged in, too, that’s fairly
near to wher your PC/Modem are. Don’t pick up the phone yet.
You’re about to enter a command string to the modem, so you’ll need to have
the PC powered up and talking to the modem with whatever piece of
communication software you use. In the case of Procomm, Smartcom,
SmartTerm, Zterm, etc., it’s simply a case of just firing up the software
and getting to a terminal screen with the “OK” prompt from the modem. If
you normallly use first Reader or Robocomm, then you’ll need to fire up the
Terminal Session for those packages and again just get to an OK prompt. Don
’t dial out a number.
Now type this:
“ATX0d1;”
(without the quotes) and you should hear (if you have the modem’s speaker
on) is that the modem will pick up the line (dialtone heard), then dial a 1
and finally drop back to command mode (OK prompt on you screen) while
holding the line open. The next bit is easy or more difficult depending on
the accessibility of your modems? Leads. i.e. internal or external modem.
Now pick up the phone and listen.
THIS time, it’s going to be your modem that may “time out” before your phone
line does. Check the modem’s lead, plugs and sockets by physically getting
hold of them and just gently pushing and pulling on the lead at both ends.
You’ll find on these type of plugs that there is possibly a couple of
millimeters of “play” even when the plug is fully seated in it’s socket.
This is enough for our purposes. Again, be gentle. If there is a dodgy
connection, it won’t take a lot of movement before it becomes apparent in
the phone you are listening to. No noise? If your modem hasn’t already
timed out, drop the line by typing “ATH”. If you did hear some crackling
from that, then you’ll need to get that lead replaced. It could be just the
contacts of the plugs that have become a little tarnished. A good ink
eraser with a fairly sharp edge should clean these up nicely.
Modems With a Rockwell Chipset
OK, you’ve carried out all the above and you are still getting poor high
speed connects with your modem. Now it’s going to matter exactly what type
of modem you have, and whether it has a Rockwell chipset in it or not. How
do you find out? The easiest way (and most standard) is to type either AT&V
or AT14. If you have a Rockwell chipset, from the former you’ll see a
complete configuration dump starting with “Active Profile” then “Stored
Profile 0” followed by “Stored Profile 1” and finally “Telephone Number
Stores”. The latter should return a couple of rows of checksum digits (up
to 4 rows) which are the capabilities of the modem in “hex.”
If you have a Rockwell chipset, follow this procedure:
1. Dial into another modem [a BBS or other service provider] from a terminal
screen (not automatic with a script-manually)
2. Do whatever you need to get your Login prompt [if your service does
immediate PPP or immediate TELNET, use a different service].
3. Pause (do nothing) for at least 1 second
4. Type”+++” (without the quote marks-just the pluses)
5. The modem should now have dropped back into command mode and you cshould
be looking at an “OK” prompt but you will still be online…
(You’ll need to be fairly sprightly, as you may lose the connection if you
aren’t quick enough…)
6. NOW you can type AT%L%Q[Return]. The modem should return 2 figures on
successive lines like 20, 8 or something.
These are the Line Level (%L) in –dbm and the Eye Quality Monitor (%Q)
index. In the example above, that would be 20dbm (reasonable) and 8 (also
reasonable). Higher figures mean worse connections. Anything higher than
about –24 with the first, and you’ll be seeing bad connects or possibly none
at all. Higher than 15 on the second, and you’ve got real line problems on
your circuit that your Telco should be able to sort out.
When you’ve finished, you might like to go back online with ATO (not zero)
and then log off normally. You may find you get logged off anyway after you
’ve got the response to %L%Q…
If you do get bad figures from these tests, you’ll need to contact your
Telco to try and get you line improved.
Other Modems
If you have a USR based modem (and there are some “badge engineered” models
about), then chance are you will be able to use AT16 for your checking.
This can be done either online (see above for how to stay online but get
back to command mode…) or offline, as the USR chipset “remembers” the
figures it got from the last connect you made. The bits your are interested
in are BLERS. These are “Bit Link Error RateS”. Ideally, this figure
should be 0. If it is 1 or 2 after you have been online for a while, then
you probably have nothing to worry about. If it climbs much higher over,
say, a 3-4 minute connect, then you are probably suffering from noise or low
level or both, as in the Rockwell situation above. If you want to know what
the rest of the figures mean, consult your modem manual.
Unfortunately, the USRs do not give an indication of the actual receive
carrier level in decibels/milliwatt (dbm).
If you have neither of these types of modem, then you are going to have to
consult your manual.
If you’ve got noise and a low line level, you need to contact your Telco
provider. Explain to them that you are using a modem on your line, you are
getting poor cct quality figures from your modem, and that the line level
is low. Your are entitled to have this problem corrected. Make sure that
you say there is nothing wrong with your normal voice communications (if
that is the case…)otherwise they will just do a normal line check. If you
are on a digital exchange, ask them if you can have the AGC (automatic gain
control) turned OFF and your line setting at the exchange, set to position
“5”. In most cases this should give you a good cct and level and cure your
connect problems at a stroke.
If you are experiencing the noises described earlier, be warned that it may
take several visits and tests by the telephone company before the cause of
the problem gets rooted out.
Eric
IST
-----Original Message-----
From: Richard P. Eldridge <eldridge@duo-county.com>
To: ascend-users@bungi.com <ascend-users@bungi.com>
Date: Monday, April 06, 1998 8:05 PM
Subject: (ASCEND) 56K modem disconnects
>Has anyone had any complaints with the 56K Flex modems disconnecting at
>random? I have three Max 4048 boxes with 2 - 24 count modem cards in each.
> I've had quite a bit of trouble here and starting to hear some complaints
>with my customers. Do you have any suggestions?
>
>_________________________________________________________________________
>Richard P. Eldridge eldridge@duo-county.com
>Network Data Engineer Voice: (502)343-3131
>Duo County Telephone Coop. Fax: (502)343-3800
>1021 West Cumberland Ave.
>Jamestown KY 42629 http://www.duo-county.com
>_________________________________________________________________________
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