SLIP II (for PCs) TROUBLE-SHOOTING GUIDE

There are many different problems that can occur when installing SLIP. First make sure that you initiate SLIP correctly: from Windows, make sure you start TCPMAN before you start any other network application. From DOS, make sure you type TCPSTART before you start anything else. Also be sure that your modem is at least 9600 baud as slower modems do not work with SLIP. Also check for minimum machine requirements: Windows machines must have at least a 386 CPU with at least 4 megabytes of memory. Dos machines need at least 640 K of memory and should be running DOS 5.0 or higher.

Most SLIP problems fall into two main categories:

1. "The Modem does not respond to SLIP at all. I do not hear a dial tone, nor do I hear it dialing," or
2. "The modem dials the phone number, I hear it hand-shaking' (a loud static noise), but something fails after that because network applications do not work."

This type of error can manifest itself in a number of ways. The most common errors you will see are:
From Windows, you see a message that says, "Modem not Responding, script aborted," or

From DOS you will see something similar to this:
"Attempting to Dial Phone
? Warning: Unknown address for port.
Assuming \x03E8
? Warning: Unknown hardware for port. Using the BIOS as
BIOS3. Unimplemented"

There are a number of reasons this could happen:

* Check the COM port.
The problem is usually due to an improper setting of the COM port or IRQ during installation. Try and verify that the settings you have are correct. An easy way to see what COM port your modem is on is to use Terminal in Windows (found under the Accessories Window). Start Terminal, then open Communications under the Settings' menu. At the bottom right hand corner choose COM1, then click on OK. Now hit some keys; if the letters appear on your screen, then your modem is at COM1. If they do not, repeat the process for all four COM ports until you find the port at which the letters appear. Once your find out, you can run SLIPCONF from dos to change the value for the COM port.

* IRQ Settings:
The IRQ settings are usually standard and it is unusual that the default setting would not work. If, however, you have reason to suspect otherwise, you should check with your modem manual to find out. You can then make the appropriate changes using SLIPCONF. Sometimes there is already another device using the same IRQ that will cause conflicts. You can check this by viewing your IRQs using MSD from Dos. If that is the case, you may need to change the IRQ on your modem by moving jumper pins, or change the IRQ on the other device.

* IRQ address:
There is also an 'address' at which any computer finds the correct IRQ. This is generally standard if you are using COM ports 1 or 2. If, however, you are using COM 3 or 4, the settings are not always the same. You should check to see the actual address of your IRQ using MSD (from DOS) and see if it matches the value returned by SLIPCONF. If it doesn't, you should change it accordingly.

If all of the above problems have been eliminated, then move on to the next section of this document and check the problems listed there.

Or you may be getting one of many other manifestations of the same problem; it depends on a number of things. It could be garbage appearing on your screen when you try to connect.

NOTE: When you start TCPMAN in Windows, it has not succeeded making its connection until you see a message that looks like this: "bootp successful. MYIP = 128.248. . . " The connection is not functioning until you see that message. Once you do see it, DO NOT exit TCPMAN. TCPMAN must stay running to keep the connection active. You need to minimize it instead. You can do this by clicking on the down-arrow at the upper right hand corner of the TCPMAN window. Once you are finished, you can hang up the phone by going into TCPMAN, clicking on DIALER, then BYE. After it has hung up, you can then exit TCPMAN.

Problems occurring at this stage are often due to improper modem initialization. There are many different kinds of modems and computers out there and SLIP must be told how to communicate with them. This is done by choosing the proper initialization string while installing SLIP. It can also be changed by running SLIPCONF from DOS. How do you know the proper initialization string for your modem? It is usually included in the manual that comes with the modem. It will usually look something like the default string that we provide with SLIP (e.g. ATE1V1&D0). The different letters and numbers have different meanings that tell the modem how to respond to certain actions taken by SLIP. A string that works with most modems is AT&FE1V1&C1&D0.

If you do not have your manual, or the string you tried did not function, we have an extensive list here at CSO. If you call us or send email to consult@uic.edu with your modem brand, model, and speed, we will be able to provide you with the latest published initialization string for your modem. You can also look it up on our modem reference page. Whenever you change this string you should completely reset your modem. If the modem is external, turn it off and on. If it is internal, turn off your computer for 20 seconds before restarting it.

* Modem Speed:
Another problem could be that your computer is not communicating with your modem at the proper speed. If you have an external high speed modem, it often occurs that the chip through which your computer and modem communicate is much slower that the actual speed of the modem. Many computers have an 8250 UART chip which has a maximum speed of only 9600 baud. That means the total speed of an external modem might be severely limited by this chip. In any case, you should definitely set the speed to 9600 hundred using SLIPCONF during trouble-shooting (regardless of the modem speed) to avoid compounding problems. It can be increased after the other problems have been found and alleviated. You can jump to the UART Chip section in this document for more details about UART chip limitations.

* Flow Control:
A problem that does not frequently occur is that the modem is not set for Hardware flow control. Some modems use Xon/Xoff flow control that will not work with SLIP. Generally, if you have the correct initialization string, there are characters in there that tell the modem to use the proper flow control if it is necessary for that modem type. If this is not the case, however, you may need to include an &K3 code into your string to ensure that it is set correctly. Some modem types even have a jumper or switch on them that make this change. Please consult your modem manual for details.

* Cables:
Your PC's external modem-to-PC cable may also not have all the wires needed for hardware flow control. Some cables often only carry transmit and receive. The correct cable uses pins 2, 3, 4, 5, 6, 7, 8, and 20. More pins are OK, but if any of the these aren't wired through, it will not work.

* Modem:
Your internal modem may not be fully compatible with your PC's data bus and/or timing; some 8-bit internal modems will not work in faster machines.

Also check that, if the modem is external, it is turned on and plugged into the computer properly. If the modem is internal, you should turn off your computer for 20 seconds after making any changes in Modem configuration.

2) Windows for Workgroups:
If you are using Windows for Workgroups, and have an external modem, you must upgrade the SERIAL.386 files in order to insure reliable communications via any 16550 UART (Universal Asynchronous Receiver Transmitter) chip. You can download the new SERIAL.386 file from ftp.microsoft.com (/Softlib/MSLFILES); the file name is WG1001.EXE.

3) No SLIP icons in Windows.
When you start Windows after installing SLIP, it should create a Window called SLIP II with 5 icons within it: Telnet, TN3270, TCPMAN, PING, and FTP. There are some configurations of Windows that hinder the automatic creation of these icons upon the next start up. If they were not created, you can create them by choosing RUN from the FILE menu, then type c:\uicadn\adnicons (assuming that you allowed SLIP to be installed in the UICADN directory; if not, change the name accordingly).

You can also create Windows and icons manually; consult your Windows manual for details.

4) UART Chip problems:
Universal Asynchronous Receiver Transmitter chips have caused problems for a number of people using SLIP. External modems depend on these chips to communicate with the computer. When SLIP installs itself on your computer, it often misreads the UART chip information and tells you that you have a faster chip that you really do. Some chips, such as the 8250 or 16550, are slower and less reliable; they are only able to transmit reliably at 9600 baud. Sometimes SLIP will think that you have a faster CHIP and offer you a default modem speed faster than the speed actually available. Always assume the worst and choose 9600 to start. If it works, you can always increase it slowly to see what works and what doesn't.

You can also use MSD from Dos and see what it tells you about these chips. If you do have a slower one, you may want to upgrade to a faster 16550A chip. They cost about $50 or so at any computer store. You could also purchase a new serial card that has a faster chip.

5) Netid or password not accepted.
If our dialin servers do not accept your netid or password, there are a number of things that could be occurring. If you use a CMS account, the TACACS authentification on our dialin servers checks there first. If it doesn't find you, it will check the other machines: tigger and icarus. For tigger and icarus your netid and your login-id are the same, so there isn't usually a problem with authentication. If you only have a CMS account, however, you also need to consider this: your login ID is not always linked to your netid as it should be. You can check by typing ACL in your CMS account. If you see your netid in the netid field, then you should be able to login using that netid and password. If it says "none," then your netid will not work and you will need to use your Userid (U12345) instead. If your netid is not linked to your userid, call the CSO or email us at consult@uic.edu and we can fix it for you.

The problem may also be that your netid (or userid) was entered incorrectly or understood by SLIP incorrectly. There is a bug in the script that sometimes puts an extra character at the end on a netid after it's entered. You can change it from Windows in TCPMAN by choosing SETUP from the DIALER menu. In this case you would just type in your netid without the @uic.edu part. From DOS you can change it by running SLIPCONF. In this case, however, make sure you type in the whole thing: netid@uic.edu (e.g., jsmith12@uic.edu). If the netid is still wrong when you use TCPSTART, then you can edit the c:\uicadn\uicslip.ini file manually and change it there. Be careful, however, not to change anything else in that file.

Also, for passwords to function correctly, you must already have logged onto your account once. If you haven't, do so at the next opportunity so that our dialin line servers will recognize you.

• What is the computer brand and model:
• What is the modem brand, speed and model:
• Is the modem internal or external?
• Does the modem dial when you attempt to start SLIP?
• Does it work from either DOS or Windows?
• What phone number are you dialing?
• What is your netid/userid with which you logon? (i.e., the one you entered when you installed it)
• Did the problem start suddenly, or is the first time you are trying to connect?
• Does the modem behave properly with other communications software?
• If TCPMAN does function, do you see the MYIP=128.248...' message at the end, or do you see Script aborted'? What is the last thing you see in the script?
• If your modem is not dialing, how do you know that the COM port setting is correct?

While in TCPMAN, click on DIALER, then click on EDIT SCRIPTS, then choose LOGIN.CMD. Go to the third line down that says, "# trace on". Delete the # sign. Click on FILE and then EXIT and choose to SAVE the document as you exit.

Now click on DIALER and then LOGIN to dial again. Now when it runs it will show the entire script by as it does. Be sure to include the last 10 lines in a problem report to us. We will then be able to diagnose the problem much better.