Speaking of MTU, it appears that the new Windows 98 OS now sets the MTU for
dial-up adaptor to 576, instead of 960, and PC-SKIP no longer will function
correctly, unless you change it. Has anyone else run into this problem?
-----Original Message-----
From: Alexei V. Vopilov <[EMAIL PROTECTED]>
To: [EMAIL PROTECTED] <[EMAIL PROTECTED]>; Joe Provino - Sun BOS Software
<[EMAIL PROTECTED]>
Cc: [EMAIL PROTECTED] <[EMAIL PROTECTED]>
Date: Friday, June 26, 1998 3:23 AM
Subject: Re: MTU problem with Dial-up on NT
>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.
>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\T
cpip
>:>
>:> 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
>:
