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.cac.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.