RAS Configuration May Change When You Install Multiple ISDN Cards on the Same Computer

ID: Q237968

The information in this article applies to:

SYMPTOMS

When you install multiple TAPI devices on the same computer, such as ISDN PRI cards, the RAS configuration specified for the port could change. Typically, the problem occurs when you install two ISDN cards of the same type on the computer.


CAUSE

The problem occurs because the device list is maintained in descending order in the registry. When NdisWan.sys initializes, it registers the second adapter before registering the first adapter with TapiServ. This causes the addresses and names to get swapped.


RESOLUTION

A supported fix that corrects this problem is now available from Microsoft, but it has not been fully regression tested and should be applied only to systems experiencing this specific problem. If you are not severely affected by this specific problem, Microsoft recommends that you wait for the next Windows NT 4.0 service pack that contains this fix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information on support costs, please go to the following address on the World Wide Web:

http://www.microsoft.com/support/supportnet/overview/overview.asp
The English version of this fix should have the following file attributes or later:

   Date       Time     Size      File name     Platform
   -----------------------------------------------------
   07/20/99   03:21p   153,872   Rascfg.dll    x86
   07/20/99   03:19p   233,744   Rascfg.dll    Alpha

NOTE: If this product was already installed on your computer when you purchased it from the Original Equipment Manufacturer (OEM) and you need this fix, please call the Pay Per Incident number listed on the above Web site. If you contact Microsoft to obtain this fix, and if it is determined that you only require the fix you requested, no fee will be charged. However, if you request additional technical support, and if your no-charge technical support period has expired, or if you are not eligible for standard no-charge technical support, you may be charged a non-refundable fee.

For more information about eligibility for no-charge technical support, see the following article in the Microsoft Knowledge Base:
Q154871 Determining If You Are Eligible for No-Charge Technical Support


STATUS

Microsoft has confirmed this to be a problem in Windows NT 4.0.


MORE INFORMATION

Some ISDN adapters, such as USR PRI ISDN cards, have multiple channels on the same card. USR PRI has 23 channels. When the first card is installed, the first channel of the first adapter is mapped to the RAS port ISDN1, the second to ISDN2, and so forth. When the second card is installed, the first channel of the second adapter is mapped to the ISDN24, second to ISDN25 and so on. The ports can be configured for "Receive calls as a RAS server" or "Dial out as a RAS client".

However, when you restart the computer, the ports are remapped. The new configuration maps the first channel on the first adapter to ISDN24, the second channel becomes ISDN25, and so forth. The first channel on the second adapter becomes ISDN1, the second becomes ISDN2, and so forth.

This affects the RAS configuration assigned to the particular port/channel. If all the channels on the first card are originally configured for dial-out only (client), and all the channels on the second card are configured for receive only (server), after you restart, they are swapped such that all the channels on the first card now are configured for receive only, and the second card for dial-out only.


Before restart: 


Port Address 6-23-0 6-22-0 .....6-1-0   4-23-0  4-22-0 ... 4-1-0
Friendlyname ISDN46 ISDN45 .....ISDN24  ISDN23  ISDN22 ... ISDN1
Role         Server Server .....Server  Client  Client ... Client
After restart: 

Port Address 6-23-0 6-22-0.....6-1-0  4-23-00 4-22-0 ... 4-1-0
Friendlyname ISDN23 ISDN22.....ISDN1  ISDN46  ISDN45 ... ISDN24
Role         Server Server.....Server Client  Client ... Client

Additional query words: 


Keywords          : kbbug4.00 kbfix4.00 
Version           : winnt:4.0
Platform          : winnt 
Issue type        : kbbug

Last Reviewed: August 8, 1999