Dial-Up Connection Drops
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Why Did My Penn State Successful Dial-Up Connection Fail to Connect or Drop after Connect?
Why Did My Penn State Successful Dial-Up Connection Fail to Connect
or Drop after Connect?
A Checklist
by H. D. Knoble
http://its.psu.edu/
http://aset.psu.edu/
http://gears.aset.psu.edu/
24 January 2005
The Pennsylvania State University
Academic Services and Emerging Technologies
and
Penn State Administrative Information Services
Once an Access dial-up connection is established at a data rate
compatible with your modem and serial port to Penn State TCP/IP
services, the connection may drop; the following is a checklist of
possible reasons for this specific scenario. We recommend that you copy
and check this list before calling for technical assistance if and when
you experience seemingly random connection drops (disconnections). This
not only will help us; but it will help you improve the reliability of
your microcomputer communications. The checklist follows:
(1) a) The ITS Serial Protocol (dial-up) servers (863-2222, (or
8863-2222, from phones at University Park Campus), may drop data
(drop the modem connection) after 10 minutes of inactivity.
"Inactivity" is defined as no modem data exchange. E.g., using Eudora
to compose a letter taking more than 10 minutes to compose it
while using no other Access clients; while connected using any
Windows applications that are not Access clients - like MS Word
Excel, etc. - for more than 10 minutes at a time would cause no modem
data exchange and so would be considered "inactivity."
"Inactivity" is defined as no Internet data exchange. Using
FTP (directly or through your favorite WWW browser) causes
lots of "activity". So does general Web browsing.
For Modem specifications, phone numbers for Commonwealth Campuses,
etc., please see Web page:
http://css.its.psu.edu/internet/dialup/modem.html
b) Information Technology Services (ITS) tests systems nearly every
day between 5:00 a.m. and 7:30 a.m. During this time, one or
more services may not be available.
c) The Information Technology Services (ITS) and Tellecommunications
and Network Services (TNS) can and do experience technical problems
with both the Penn State Backbone (Network) and the larger
Internet Service Providers (ISP's) to Penn State; In this
case, the problem is ours and not yours. We suggest that you
run through the rest of the check list here before assuming
that the problem is not at your end (statistically the
probability is overwhelming that this is true). After
running through the rest of this checklist, if you can
get dial-up Web access visit the page:
http://status.css.psu.edu/statpage/status.html
to check the current status of the various Internet
Services. If you cannot get dial-up Web access, then
call one of the Helpdesks to see if there is a PSU or
other know network outage. Those phone numbers are:
ITS - Computer Bldg. Help Desk: (814) 865-0827
ITS - Willard Bldg. Help Desk: (814) 863-1035
TNS - TNS Help Desk: (814) 863-HELP(4357)
(2) Hours of availability for the Penn State Data Backbone
are advertised as follows by ITS and TNS:
"Normal operating hours for the Data Backbone are from 7:30 a.m.
to 5:00 a.m.; 5:00 a.m. to 7:30 a.m. is the time designated for
normal maintenance. Most often, the historical record shows that
the maintenance period was given over to normal operations.
However, normal maintenance may disrupt the data backbone so no
guarantees about quality are made for the normal maintenance
time." Also see TNS Web page:
http://tns.its.psu.edu/help/networkOperationsCenter.html
The AIS Web page:
http://ais.its.psu.edu/access/hours_avail.html
and the Library Web Page:
http://www.lias.psu.edu/hours/
from the left panel.
(3) When running Windows Dialup Networking click My Computer/
Dialup Networking and right-click the connectoid that you
are using and choose Properties. If there is a "Dialing" tab
click it. UNcheck "Enable Idle Disconnect" and "Disconnect
when connection may not be needed" boxes. Click OK.
(4) Double-Click My Computer, Double-click Dialup Networking folder,
RIGHT-click the "Penn State Connection" (or ITSPPP) icon, choose
"Properties" menu item. On the General tab of the resulting screen,
click the Configure button. Make sure Maximum Speed is 115200 for
V.90 modems. Then click the Connection Tab. Under "Call preferences"
section of the screen make sure that the "Cancel the call if not
connected within" number is at least 120. Click OK; Click OK again.
Retry the connection if you changed increased this setting.
(5) For Windows Access clients, a Windows GPF (General Protection
Fault) may cause the connection to be dropped. Please see:
http://ftp.aset.psu.edu/pub/ger/documents/Where95&NT.htm#Freeze-Ups
Typical causes of GPF's may be caused by lack of PC maintenance;
see:
http://ftp.aset.psu.edu/pub/ger/documents/Where95&NT.htm#MinimalMaintenance
and for Windows XP: http://ftp.aset.psu.edu/pub/ger/documents/xpmaint.html
(6) For Outlook Express if your connection drops after sending/receiving
Email, check the setting: Edit/Options/Connection; make sure the box
labeled, "Hang up after sending and receiving" is NOT checked.
(7) There are lots of external (environmental) causes for faulty
modem communications, especially (but not only) for high-speed
(up to 56K V.90) connections. Most of these are related to the
phone line itself. Sometimes (but rarely) this is a Verizon
problem. More often the problem is related to the phone line
between the phone jack and modem, or serial connection between
modem and microcomputer serial port. Our recommendations, based
on years of experience and experiments involving actual cases,
follow:
a) Do not route the phone line within three inches of any
electrical cord or extension cord, or PC CPU cord, or
Printer cord, or Monitor cord, or any electrical appliance
or power supply. This often means taping or stapling the
phone line away from such places between jack and modem.
Symptoms are random dropping of the line, problems with
TCP/IP clients, logging in, etc. Inductance from electrical
lines wreaks havoc with phone lines.
b) Do not route a phone line being used by a modem through
answering machines or phone mail systems. Some of the
"smarter" ones have been known to intercept/inject data,
which of course can have undesirable results.
c) Do not route a phone line underneath a carpet since people
probably will walk on it, thus crushing the very fine wires
therein. The same is true for running phone lines where
doors will close on them, etc.
d) Do not use old phone lines from jack to modem. Use a new phone
line of the correct length, without splicing (splicers also
have been known to cause loose connections, and thus problems,
in some cases). Switch phone line cables with a friend's
working cable to verify this problem.
e) For external modems, if your serial adapters or serial cable
is old, adapter pins bent, or cable cracked, replace them.
Make sure your serial connections are TIGHT. Parts (a) and
(c) above also apply to serial cables. Switch cables
with a friend's working cable to verify a cable problem.
f) For internal modems, and for all microcomputers in general,
dust buildup on internal components compromises built-in PC
cooling systems. While any PC is running, fans circulate air
around internal components. We recommend that after unplugging
all related electrical connections, you remove the CPU cover
and carefully blow dust off all computer components, including
internal modem cards, at least once a year; compressed air cans
(purchased where electronic components are sold) or reversible
vacuum cleaners may be used this purpose. Dust free components
PREVENT communications problems.
g) Surge protectors for both computer power and phone connections
are recommended. But we recommend that you unplug your computer
AND modem's phone line during electrical storms (which may do
more than interfere with a TCP/IP dial up connection). Note that
cheaper power strip surge protectors become less effective with
each surge; after three or four major surges they may not be
surge protecting at all. It is possible to have a phone line
surge protector installed by Verizon which will more
effectively protect your phone equipment. Most modems are quite
susceptible to power surges; if your modem suddenly quits
working after a storm, it may have been permanently damaged.
One way to test this possibility is to move the modem (card)
to a different computer at a different location, wiring, PC,
operating system, etc. and see if it works there; if not,
the modem has likely been damaged.
h) Probably the most practical way to avoid most electrical problems
noted in 7.g above is to use a Uninterruptable Power Supply
(UPS). These are now inexpensive and will protect both
PC's and phone lines.
i) Never plug any microcomputer equipment into an electrical
outlet that is controlled by a dimmer switch.
(8) When dialing with a modem through a phone with the phone company
feature "Call Waiting", if "Tone Block" is not activated
(i.e., Call Waiting is not canceled for this call) then if someone
calls after such a dial-up connection has been made, it is highly
likely that the data connection will be dropped. (Please see page
43 of the 1995-1996 Verizon phone book for State College for
information.) That in fact is most often the case if the connection
is via ITS or TNS Serial Protocol servers. To activate Tone Block
prefix the four characters "*70," (down town State College) or
"169," (University Park) to the phone number to be dialed by the
modem; for example: *70,863-2222. For Windows Dialup Networking
just prepend one of the above Tone Block strings to the phone number.
(9) If you do not get a dial tone and do have "Phone Answering" or some
other Telephone Company answering service, you may need to insert a
pause for a few seconds before attempting to dial. You can do this
by adding four commas just before the phone number. (This assumes
that your modem can be accessed via Start/Settings/Control Panel
Double-click Modem Icon, choose the mdem in the white screen by
clicking it once, Click Diagnosics tab, click the appropriate COM
port and then the More Info... button. If the modem's make/model
etc. display then your modem checks out and you might apply the
delay recommended here.)
(10) If after dialup you CONNECT at a reasonable speed, but all
of your Internet clients fail to work, use the PING or
under Windows NT/2000/XP the Tracert tool to determine
if there is a viable Internet connection. For example,
click Start/Programs/MS-DOS Prompt and issue the command:
PING 128.118.25.3
Exit
If this times out and the Helpdesk says that University system
in question is working properly, and none of the above
check list items apply, try Un-installing TCP/IP and
after Shutdown/restart Re-install TCP/IP. This is done
via the Network Icon in Control Panel. If you are not competent
to do this, get help. For cases where dialup connects but Internet
clients fail, this Un-install/Re-install has proven productive.
(11) If you are using an external modem, check:
a) Your serial cable from modem to PC. Switch serial cables by
borrowing one from a neighbor or friend. This will help isolate
the problem if it is the serial cable or connectors.
b) The PC Serial port that the modem serial port is plugged into
may not be able to handle a fast modem. This can be true even
on a new computer. In this case the serial port UART (Universal
Asynchronous Receiver/Transmitter) may not be a 16550 (buffered)
UART. To determine this is sometimes tricky. If you modem runs
without disconnecting at 9600 bps or 19200 bps but not at higher
speeds, it is almost a sure thing that you have one of the
slower UARTs. For ITSSLIP use the UARTTYPE subcommand at the DOS
Prompt to display UART information. For ITSTWIN under Windows 3.1,
exit Windows and run the program: MSD and choose the Communication
Ports menu option to display UART information. Windows 9x and NT
will usually correctly determine the serial port capabilities.
Again, if the modem works with reduced (DTE) speed, then you
most likely do not have a buffered serial port. The solution
is to either use an Internal modem (which has a built-in buffered
serial port), or to add a buffered (fast) serial port.
(12) There may be COM Port conflicts. This can be COM Port
addresses on microcomputers where COM Ports are configured with
BIOS Setup incorrectly. In this case if the BIOS Setup were changed
the modem may not even be accessible (won't dial).
Uninterruptable Power Supplies (UPS's) often come with software
and a serial cable. The software works with Windows, COM1, and
the Windows OS's to effect a Shudown when their is a power outage.
Under Windows NT/2000/XP this may run as a service or as a startup
program (e.g., ups.exe).
In addition to COM Port conflicts may be IRQ conflicts. Note that
with normal (default) IRQ settings, COM1 and COM3 share IRQ 4 and
COM2 and COM4 share IRQ 3. This means that if you're using COM4
for an internal modem, for example, then you may not have any COM2
software (e.g., scanner) active while the modem on COM4 is being
used. If you do, in general the modem won't work at all, but it
may dial and then sporadically disconnect depending on a lot of
factors. Detaching hardware from COM2 won't solve the problem in
necessarily. Make sure there's no software (e.g., drivers, programs
etc. started for a COM Port that shares an IRQ with your modem
while you're using your modem.
These conflicts may be introduced by installation of communications
software, or by changing networking/modem settings through various
"Control Panels". One way to prevent inadvertent changes of such
information is not to attempt to install communications or networking
software or to make changes to control settings unless you are
confident that you know what you are doing.
(13) If you are running Windows and seem to have problems connecting
or dropping at random times just after the modems try to connect, it
may be that your (internal or external) modem UART or CPU cannot take
the higher speed modem traffic at the input/output level that
Windows 9x/NT estimated from the device driver properties
supplied by the manufacturer. For example a 56K modem might have
higher suggested throughput than the COM Port can take. In this
case you can make an adjustment to the PORT properties by changing
(lowering slightly) the Transmit/Receive Buffer speeds (methodically)
as follows:
In the Windows 9x Dial-Up Networking folder right-click the
connectoid in question and choose Properties. Then (left-click)
the General tab, then Configure button, then Connection Tab, then
Port Settings Button, and slide both "Receive Buffer" and
"Transmit Buffer" speeds back to the "Low"(1) setting. Then click
OK, OK, OK. If this corrects the disconnect problem, then one
notch at a time increase these "Buffer" speeds, one at time,
connecting between each change, until you get a failure; then
move the one last changed back toward Low again.
(14) Not infrequently, the modem drivers and or Flash ROM distributed with
modem itself are buggy and not current. If connections are not solid
we recommend visiting the PC or modem vendor's Web pages for
downloading the latest drivers. Read all extra information and
documentation before installing newer drivers and/or Flash ROM.
Do not upgrade drivers of Flash ROM without such documentation.
You may have to write "technical support" to get the documentation
or to verify that a specific upgrade is needed for your modem.
Incorrect upgrade of Flash ROM can cause the modem to become useless.
(15) Under Windows, if you get connected but your correct Access
Userid/Password will not verify, then it may be (A) that your Access
userid and or password are incorrect. Double-check the spelling of
both, and make sure both are in all lower-case. (B) that the connectoid
in question has Microsoft Encryption turned on. For Windows 9x right-
click the connectoid and choose Properties then Server Types tab; make
sure the box "Require Encrypted Password" is UNchecked. For Windows NT 4,
choose the "Phone Book Entry to dial" and click More and choose "Edit
entry and modem properties"; then choose the Security tab and make
sure that the bullet "Accept any authentication including clear text"
bullet is chosen; that is, do not choose either of the other two
"encrypted" options.
(16) Also see the Trouble Shooting Guide by Chris Quirke at:
http://users.iafrica.com/c/cq/cquirke/dundebug.htm
(17) Is your modem a "Soft" HPC, HFC or Conexant (formerly US Robotics)
Winmodem? These modems use software drivers as substitutes for
some of the modem's microchips to effect some parts of the
modem communications. This reqires significant amounts of CPU.
We recommend a minimum of 200MHz processor with 32MB RAM
if you purchase a Soft Modem to install in an existing PC.
Some PC's, for example, some Hewlett Packard PC's, come with
Conexant Soft56 Data Fax PCI Modems pre-installed. These
These usually work well as the newer faster CPU's and adequate
RAM support them. Too slow a PC or other factors covered
in this Checklist may cause slow connections or connections
For more information on Soft modems please see:
http://www.56k.com/reports/winmodem.shtml
Also note that since Soft modems need special Windows drivers
they are not usable from a DOS system via Windows Statup or boot
disk. They may work under Windows MS-DOS or Command prompt;
they may not work under Windows Me MS-DOS command prompt
since Windows Me shares non-standard serial port IRQ's used for
Soft modems with several other devices.
Thus, in general, older DOS programs that may be used to retrieve
data via modems would have a better chance of working using an
External (dumb) modem connected to COM1 or COM2 serial port.
(18) For older systems (DOS and Windows 3.1 clients) screen savers (TSR's)
can interfere with communications. Typical symptoms in this case
are "random" line drops (when screen saver kicks in/out), and
file transfer via FTP interrupted and aborted. We do not recommend
running screen savers or other timer-related DOS Terminate and
Stay Ready programs when using modems--period. For Laptops,
power managment can shutdown power to resources needed by a
TCP/IP session.
Similar problems can happen with Fax software which if loaded
will interfere with DATA transmission (access to PSU Serial
Protocol Servers for dial-up Internet connections). Using Fax
software can also leave the modem in Fax mode; if a modem
reset (AT&F and sometimes ATZ) is not done before DATA mode
is used, the modem WILL dial a data line but login scripts
will either not work at all or work with anomalous results.
Regarding non-USA made modems, when some of them power up or
hang up, they enter Auto-Answer mode. Thus immediately before
or after use of these modems anyone calling your home phone
may get a data tone. To circumvent this, use the modem subcommand:
S0=0 in the modem setup string.
-----------------------------------------
ACKNOWLEDGMENTS
Thanks to Peter M. Weiss, John Kalbach, Jim Leous, Dan Bernitt,
Chris Sacksteder, and Kolawole Segun for technical contributions
in this document.