Hi, folks,
The following is not the only solution to MTU on Windows NT. Actually,
in Windows (no matter NT or 95) IP askes for MTU value during its
initialization phase. If your SKIP is loaded and initialized before IP
is loaded, the SKIP should be able to intercept the request for MTU from
IP and respond accordingly.
Just for your information.
Hu Jian
Uibiquity Lab
Kent Ridge Digital Labs
(65)874-6642
Joe Provino - Sun BOS Software wrote:
>
> There appears to be a problem with Dial-up Networking on NT 4.0 with the
> maximum size of a packet that can be transmitted (called MTU).
>
> The problem is that the Microsoft software fails to ask for the MTU and
> must therefore be assuming a constant. This works without SKIP encryption but
> fails when encryption is enabled because SKIP adds some headers increasing
> the size of the packet beyond the Adapter's MTU.
>
> What is supposed to happen is that when IP asks for the MTU, SKIP intercepts
> the reply and subtracts the size of the additional headers from the MTU
> returned to IP.
>
> Since IP doesn't appear to be asking for the MTU, SKIP does not get a chance
> to reduce the MTU.
>
> There is a workaround that requires setting the MTU in the registry.
>
> I've found some information in the April '98 MSDN library.
>
> The Title is "TCP/IP and NBT Configuration Parameters for Windows NT".
>
> The registry value that needs to be set to specify the MTU is called "MTU" in
>
> HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\NdisWan<n>\Paramters\Tcpip
>
> MTU DWORD <value>
>
> <n> is a number, e.g. NdisWan7
>
> <value> is the Adapter's MTU - 134, e.g. 1500 - 134 = 1366.
>
> This _should_ fix the problem.
>
> jp
