On Tue, Oct 26, 1999 at 11:28:48PM +0100, Steve Dodd wrote:
> On Tue, Oct 26, 1999 at 02:35:49PM -0300, Eric Dahnke wrote:
> > I thought that any character string in any transmitted data is not dangerous
> > if Hardware Flow Ctrl is used. What you guys are talking about is only
> > dangerous if flow control is software or Xon/Xoff, or no?
> No, it's always dangerous if your modem looks for +++ in the data from the
> remote modem as well as in that from the local host (which is a bit broken),
> or if you can persuade the local host to send some supplied data back (i.e.
> with a ping packet or similar).
This is generally only true for "TIES" modems. TIES modems look
for the escape sequence with no bracketing delays. It was an attempt by
some modem manufacturers to get around the Hayes Hayward patent.
Unfortunately, there are still plenty of TIES modems being produced and
sold, even though they really are incompatible with binary links like ppp
or slip. Statistical probability gives you 1 chance in 2 Meg of transmitted
data (1 : 127**3) of randomly hitting the TIES sequence. That's not
counting the kiddie-poos out there that are "TIES bombing" links using
ping packets. I don't know of anyone who can reliably reproduce the
<delay>+++<delay> of the true Hayes/Hayward style escape sequence in
a live high speed data flow.
Set S2=127 or S2=255 (as appropriate for your make and model of
modem) to kill this beast. Write it to NVRAM and add it to your init
strings, just to be sure.
> It's one of the problems with sending the link control data over the same
> path as the link data itself.
True...
> --
> Ah, but you're forgetting Rimmer directive 273 which states just as
> clearly, "No chance you metal bastard!"
Mike
--
Michael H. Warfield | (770) 985-6132 | [EMAIL PROTECTED]
(The Mad Wizard) | (770) 331-2437 | http://www.wittsend.com/mhw/
NIC whois: MHW9 | An optimist believes we live in the best of all
PGP Key: 0xDF1DD471 | possible worlds. A pessimist is sure of it!
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