Re: HTTP Stack, MTU And Fragmentation [ScanMail found this email to be virus-free.]

Sascha Siekmann <[email protected]> wrote on 22.10.2004 08:53:02:

> [email protected] wrote:
> 
> >If my domino http server receives some client requests that causes some 

> >Austrian Telekom Router (Region of Vienna/Austria ) to fragment those 
> >server sent packages wrongly for the requesting client my domino http 
> >server dies.
> >
> > 
> >
> Does that mean the http task hangs and wont recover? Do you have to 
> restart the server then? Or does the client just not receive the HTML 
file?

The http task terminates but all other domino server tasks still keep on 
running.
The client won't get any HTML file.

> 
> >On limiting the client's MTU size down to 1242 (default 1500) 
everything 
> >works fine.
> > 
> >
> What happens when you limit the MTU on the _server_ to say, 1400? ... 
> ifconfig eth0 mtu nnnn

I figured 1242 out by trial and error on the basis of a newsgroup dealing 
with
ADSL and Austrian Telekom.

> 
> >I presume the router(s) to be the problem but i want to manipulate my 
> >domino's behavior to limit fragmentions of the packages itself, get the 

> >client a definite MTU size or something like that.
> >Connections and requests from other ISPs work fine and without any 
> >problems.
> > 
> >
> You can't. You can only limit the servers MTU. Clients figure out the 
> MTU themselves ( the routers are, to be more exact by means of MTU 
> discovery). In a perfect world, this always works. Since we don't live 
> in a perfect world, some routers implement MTU discovery wrong. Check 
> your setup with this tool http://trackzapper.com/booster.html . 
> Unfortunately, only on Windoze.

It's the brave new world that makes it worth living.

Thanks a lot for your help!

> 
> -- 
> Mit freundlichem Gruß,
> 
> Sascha Siekmann
> http://spam-exitus.de
> 
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> 
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