[pptp-server] Severe performance problems

[Robert Dege]

I'm just curious, but would performance have to do with the version of
ppp/kernel that users are using?  I don't remember people posting the
versions of the PPP software that they were using, I remember more of
their config files instead.

I'm using ppp-2.3.11 with Kernel 2.2.19, and I believe that I have a
decent throughput.  Of course, despite transferring data via smb, I
haven't really tested the total possible capabilities.  But I think I
might test it today, just to see :)

-Rob

> Yes, actually I forgot to mention that performance in my case is not at all
> influenced when I switch off encryption. The same even when passing from MPPE
> 128 to MPPE 40.
> 
> Gianluca
> 
> George Vieira wrote:
> > 
> > Yes this sounds true but rememeber alot of people having speed problems have
> > switched off encryption and it still made no difference so that can't be the
> > problem.
> > 
> > thanks,
> > George Vieira
> > Systems Manager
> > Citadel Computer Systems P/L
> > 
> > -----Original Message-----
> > From: Charlie Brady [mailto:charlieb at e-smith.com]
> > Sent: Thursday, 13 December 2001 3:00 AM
> > To: Gianluca Insolvibile
> > Cc: pptp-server at lists.schulte.org
> > Subject: Re: [pptp-server] Severe performance problems
> > 
> > On Wed, 12 Dec 2001, Gianluca Insolvibile wrote:
> > 
> > > I have seen the recent thread on the 'speed' option, but I am not
> > > using that. In my case, I suspect something strange is happening with
> > > TCP flow control over the PPTP channel, but just can't imagine what.
> > 
> > An interesting theory indeed.
> > 
> > A google search for "nagle tcp" reveals a number of possibilities,
> > including:
> > 
> > http://www.icase.edu/coral/LinuxTCP.html
> > http://support.microsoft.com/default.aspx?scid=kb;EN-US;q235624
> > 
> > The key negotiation for MPPE might introduce significant latency, and that
> > could affect the TCP transmission and retransmission timers.
> > 
> > Remember too that PPTP packets must come in off the wire, go through the
> > kernel, then into pptpd, then through the kernel and into pppd, then back
> > through the kernel and into the application on the server. And vice versa
> > on the way back out to the client.
> > 
> > All this adds up to quite a lot of processing. Add to that 3DES
> > encryption/decryption for each packet.
> > 
> > Charlie Brady                         charlieb at e-smith.com
> > Lead Product Developer
> > Network Server Solutions Group        http://www.e-smith.com/
> > Mitel Networks Corporation            http://www.mitel.com/
> > Phone: +1 (613) 368 4376 or 564 8000  Fax: +1 (613) 564 7739
> >
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-- 

-Rob