Type of Service Octet in IP Header Not Initialized

ID: Q217207

The information in this article applies to:

Microsoft Windows NT Server version 4.0 SP4
Microsoft Windows NT Workstation version 4.0 SP4

SYMPTOMS

The Type of Service (TOS) octet is not initialized to zero for Windows NT 4.0 Service Pack 4 and later builds on the Alpha and x86 platforms. This results in a random value for the Precedence field in the TOS octet. Some third-party vendor's TCP/IP stacks may require that the Precedence field be set to zero, and they will send a reset to any host that does not meet this requirement, thus causing sessions between Windows NT and such hosts to fail unless the Precedence field happens to get randomly initialized to zero on Windows NT.

RESOLUTION

To work around this problem, statically start the TOS octet by setting the DefaultTOS value in the registry to some non-zero value. For additional information about how to modify the DefaultTOS value, please see the following article(s) in the Microsoft Knowledge Base:

Q120642 TCP/IP & NBT Configuration Parameters for Windows NT

To resolve this problem, obtain the latest service pack for Windows NT 4.0. For additional information, please see the following article in the Microsoft Knowledge Base:

Q152734 How to Obtain the Latest Windows NT 4.0 Service Pack

STATUS

Microsoft has confirmed this to be a problem in Window NT 4.0. This problem was first corrected in Windows NT version 4.0 Service Pack 5.

MORE INFORMATION

IBM mainframe hosts are IP hosts that are known to have this problem. The IP stack configuration on IBM mainframes can be configured to accept nonzero values in the Precedence field. Please see your IBM operating system documentation for information on how to make the necessary changes.

The third-party products discussed here are manufactured by vendors independent of Microsoft; we make no warranty, implied or otherwise, regarding these products' performance or reliability.

REFERENCES

Additional information is available in the following RFCs:

RFC 791, Internet Protocol -- DARPA Internet Program Protocol Specification

RFC 1349, Type of Service in the Internet Protocol Suite

Additional query words:

Keywords : kbnetwork ntsp kbbug4.00 nt4sp5fix
Version : winnt:4.0 SP4
Platform : winnt
Issue type : kbbug