[vpn-help] Fwd: Internet connection dies after some minutes of heavy download traffic

[Matthew Grooms]

On 5/16/2010 4:11 PM, wosgien at gmail.com wrote:
> Hi Matthew,
>
> 2010/5/16 Matthew Grooms <mgrooms at shrew.net <mailto:mgrooms at shrew.net>>
>
>
>     A few more questions ...
>
>     1) What type of connection are you using ( local ethernet, internet
>     dsl, cable, fiber )?
>

Ok. So the bulk of the traffic is NNTP ( TCP:119 ) traffic?

>
> I have a VDSL line with 50 Mbps, and I have a router Telekom Speedport W
> 722V. My PC is connected to the router via devolo dLAN powerline.
>
>     2) What is the nature of your IP traffic during high utilization (
>     ftp http, torrent )?
>

Nice :) I wish I had a 50Mbps connection to my house. In any case, does 
this involve some sort of PPP negotiation between your router and the 
telco edge? If so, that would lend credence to my theory that the issue 
is related to our kernel mode IP fragment cache code. I'm setting up a 
test system for this at the moment, but you can also try setting the 
soft MTU of your workstations network adapter to 1400 bytes or so ...

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\{AdapterID}\Tcpip\Parameters

Name : MTU
Data Type: DWORD

Set it to equal the required MTU size in decimal (default 1500)

... and disable/re-enable the adapter. This will cause TCP to use a MSS 
of 1380 or so which should avoid any IP fragmentation. After your done 
testing, you can just revert the MTU change.
>
> Downloading binary files from the usenet by means of NewsLeecher. Usenet
> provider is Giganews. NOT using encrypted server connection (SSL).
>
>     3) Does the problem still occur if all Shrew Soft services are
>     stopped in the computer management console?
>
>
> After stopping all three Shrew Soft services (but with the Shrew Soft
> Lightweight Filter still enabled), the problem still occurs.
>

Ok, definitely an issue isolated to the driver code. Thanks for testing.

-Matthew