Sounds like the main problem is your aggressive hangup due to inactivity. It should be at least 4 times as the connect time, not under half!. I suggest 6 minutes, but at least 2 minutes. If you can't adjust that, probably the next best alternative is a pre-emptive ping or something to wake up the modem about 25 seconds before you want to connect, or just ping every 5 seconds until you get a successful response On Sat, Mar 23, 2013 at 12:33 PM, Ed W <lists@xxxxxxxxxxxxxx> wrote: > Hi, I have a dialup connection (yes they still exist) and PPP with demand > dial. I have a problem with the exponential backoff sending new SYN packets > when creating a new tcp connection. The problem is that the dialup > connection takes around 23 seconds to complete (and then hangs up 10 seconds > later due to inactivitity), but by then the gaps between SYN packets is very > long... > > Unfortunately most operating systems send an initial SYN, then exponentially > backoff with intermittent resends, say after 1 sec, 2 secs, 4 secs, 8 secs, > 16 secs, etc. So what we observe is that because the dialup connection > takes so long to complete, by then the tcp connection is only trying quite > intermittently to connect, eg you might well wait another 8+ seconds before > the next syn is resent, quite easily my demand dial connection will hangup > before the retransmit is even fired... > > Does anyone have any suggestions on how I might fake this a little? I > effectively desire to simulate buffering syn packets before the PPP > connection comes up? > > Thanks for any off the wall thoughts... > > Ed W > -- > To unsubscribe from this list: send the line "unsubscribe netfilter" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe netfilter" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
