When reassembling a fragmented IP packet, the Microsoft
stack looks for a reassembly header for the fragment in order to fill the
fragment into the proper buffer. The stack creates a reassembly header if an
existing reassembly header that the fragment belongs to cannot be
found.
To guard resource use against IP fragmentation, with many
out-of-order fragmented packets occurring in a very short period of time,
starting with Windows NT 4.0 SP5, Microsoft has implemented a default limit of
100 reassembly headers. Fragmented packets that arrive when the stack has
reached the limit are silently dropped. The limit can be changed by using the
following steps to add or modify a registry parameter.
WARNING: If you use Registry Editor incorrectly, you may cause serious
problems that may require you to reinstall your operating system. Microsoft
cannot guarantee that you can solve problems that result from using Registry
Editor incorrectly. Use Registry Editor at your own
risk.
Follow these steps to change the default setting
for the maximum reassembly headers:
- Start Registry Editor (Regedt32.exe).
- Locate the following registry key:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Tcpip\Parameters\
NOTE: The registry key is one path. - On the Edit menu, click Add Value, and then type
MaximumReassemblyHeaders.
- Click REG_DWORD in the Data Type box, and then click OK.
- Type a number that represents your limit for maximum
reassembly headers in the Data box, and then click OK. You can type any whole number between 100 and 65535, in decimal
format.
- Quit Registry Editor, and then restart the computer.