[pptp-server] Session timeout

David Luyer david_luyer at pacific.net.au
Mon Jul 3 15:55:52 CDT 2000


> On Tue, 4 Jul 2000, David Luyer wrote:
> 
> > > I'm not the world's greatest C programmer, so I'm curious about a little bit
> > > of code.  Reading through everything, it appears that this causes an error
> > > and disconnects the call if it takes longer than 5 seconds to receive an
> > > echo reply.  I ask because I have a client who likes to stay connected for
> > > 4,5,6 hours at a time monitoring her AS/400 batch jobs and would hate like
> > > hell if there was some strange timeout in pptpd that was causing her to get
> > > disconnected occassionally.  Can anyone shed some light for me?  Thanks in
> > > advance.
> 
> I doubt that this is even relevant, is it?  doesn't pptpd pass control of
> the tunnel over to pppd after it's established?  Seems like this is more
> for timeouts while negotiating the tunnel in the first place..?

No, the pptpd still has to convert the HDLC frames from the pppd into GRE
frames to push over the ethernet, make sure GRE frames are in sequence
(ppp isn't designed to handle out-of-order HDLC frames, they must either
be resequenced or dropped) and so on.

The timeout in question is in the control TCP stream however.  The stream
stays open the entire duration of the "call" and if nothing is happening
then an occasional echo request is sent, with 5 seconds for a reply.  Since
it's a TCP stream there's no issue with the request/reply getting lost.

If the control stream is closed, times out or a request to terminate the
"call" is received, the ppp daemon is terminated.

David.
-- 
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David Luyer
Senior Network Engineer
Pacific Internet (Aust) Pty Ltd
Phone:  +61 3 9674 7525
Fax:    +61 3 9699 8693
Mobile: +61 4 1064 2258, +61 4 1114 2258
http://www.pacific.net.au        NASDAQ: PCNTF
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