From owner-freebsd-questions Tue Jul 11 17:09:23 1995 Return-Path: questions-owner Received: (from majordom@localhost) by freefall.cdrom.com (8.6.10/8.6.6) id RAA10460 for questions-outgoing; Tue, 11 Jul 1995 17:09:23 -0700 Received: from genesis.atrad.adelaide.edu.au (genesis.atrad.adelaide.edu.au [129.127.96.120]) by freefall.cdrom.com (8.6.10/8.6.6) with ESMTP id RAA10449 for ; Tue, 11 Jul 1995 17:09:18 -0700 Received: from msmith@localhost by genesis.atrad.adelaide.edu.au (8.6.9/8.6.9) id JAA11074; Wed, 12 Jul 1995 09:49:26 +0930 From: Michael Smith Message-Id: <199507120019.JAA11074@genesis.atrad.adelaide.edu.au> Subject: Re: PPP and demand start To: gene@starkhome.cs.sunysb.edu (Gene Stark) Date: Wed, 12 Jul 1995 09:48:48 +0930 (CST) Cc: atrad.adelaide.edu.au!msmith@sbstark.cs.sunysb.edu, questions@freebsd.org In-Reply-To: <199507111249.IAA09799@starkhome.cs.sunysb.edu> from "Gene Stark" at Jul 11, 95 08:49:09 am Content-Type: text Content-Length: 1255 Sender: questions-owner@freebsd.org Precedence: bulk Gene Stark stands accused of saying: > > >What you probably want is for the link not to drop while you have a TCP > >connection open on a remote system. Unfortunately, it's impossible > >to detect this, as an open TCP connection normally only generates > >traffic (which can be detected) when it's doing something. > > Nontrivial, but not impossible. The PPP process can track the state of the > TCP connection, as it has access to all the packets in both directions. > The "dp" package that runs on Sparc's does this, though the dp-2.3 version > I have used is not totally reliable in this respect. The PPP process under > FreeBSD does not do this type of thing, but it could if somebody coded it. This may be useful, but it offers two significant problems; a) Processing load snooping the packets (admittedly fairly trivial) b) Statefulness. > - Gene Stark -- ]] Mike Smith, Software Engineer msmith@atrad.adelaide.edu.au [[ ]] Genesis Software genesis@atrad.adelaide.edu.au [[ ]] High-speed data acquisition and [[ ]] realtime instrument control (ph/fax) +61-8-267-3039 [[ ]] My car has "demand start" - Terry Lambert [[