Alexei V. Vopilov wrote:
>
> It's probably question to Microsoft, but it seems that
> even Windows requests MTU from a NIC driver, it does *not*
> care about the response from adapters of *WAN* type.
> Thus, MTU is set always 1500 on SLIP/PPP.
That's not true. We already did this and reduced MTU for SKIP.
> However, altering the Registry possibly will help
> because it is matter of static configuration of MSFT TCP/IP.
> --Alexei
>
> -----Original Message-----
> From: Hu Jian <[EMAIL PROTECTED]>
> To: Joe Provino - Sun BOS Software <[EMAIL PROTECTED]>
> Cc: [EMAIL PROTECTED] <[EMAIL PROTECTED]>
> Date: 26 ���� 1998 �. 12:29
> Subject: Re: MTU problem with Dial-up on NT
>
> :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
> :
