"Enrique Arredondo" <atk@sbcglobal.net> wrote in message
news:fH1Uj.15927$2g1.4046@nlpi068.nbdc.sbc.com...
>
> "Brian K. White" <brian@aljex.com> wrote in message
> news:029701c8ab4b$77248c80$6b00000a@venti...
>
> ----- Original Message -----
> From: "Enrique Arredondo" <atk@sbcglobal.net>
> Newsgroups: comp.unix.sco.misc
> To: <distro@jpr.com>
> Sent: Tuesday, April 29, 2008 5:25 PM
> Subject: Re: OSR 507 using an external modem with an USB serial to
> Ethernet adapter
>
>
>>
>> "Brian K. White" <brian@aljex.com> wrote in message
>> news:036901c8a979$f60c7e50$3a8d53d0@venti...
>>
>> ----- Original Message -----
>> From: "Enrique Arredondo" <atk@sbcglobal.net>
>> Newsgroups: comp.unix.sco.misc
>> To: <distro@jpr.com>
>> Sent: Monday, April 28, 2008 3:52 PM
>> Subject: OSR 507 using an external modem with an USB serial to Ethernet
>> adapter
>>
>>
>>>I have a device called the UDS1100 made by lantronix that let's me
>>>convert
>>> any serial device into a TCP IP device, I tried this on printers and
>>> dumb
>>> terminals and it works really good. My final task is to move my fax
>>> modems
>>> that I run with VSIFAX on unix from tty1A13 or tty3E13 into this new
>>> device.
>>>
>>> Has anyone played out with this configuration and figure out a way of
>>> making
>>> the scripts or dialers that communicate with the modem to hit the
>>> assigned
>>> IP address and port so the modem works ?
>>>
>>> In the case of the printer my "model" file starts with :
>>>
>>> #!/bin/sh
>>> YOUR_PRINTER_OR_IP="192.168.2.19"
>>> PORT=9100
>>>
>>>
>>> and then I just assign the printer to that model and use /dev/null and
>>> that
>>> works out great.
>>>
>>>
>>> Can I do the same trick for the external modem thru the
>>> "Serial-Ethernet"
>>> device that wants to be called on port 10001 ?
>>> IP address= "192.168.6.182"
>>> Port="10001"
>>>
>>> Thanks
>>
>> I have used a few different serial device servers (digi, equinox, perle)
>> with fax modems and both hylafax and vsifax.
>>
>> However:
>>
>> * In all cases the device had a driver and/or daemon that provided tty
>> device nodes that work just like ordinary hardware serial ports. vsifax
>> didn't need any special config, just tell it the tty device name and
>> perhaps
>> doctor the permissions on those tty's for vsifax.
>>
>> * You are really not supposed to use fax modems over tcp like that
>> because
>> the fax protocol is very timing dependant, and the tcp/ip layer makes few
>> promises about timing, so you may or may not see a lot of failed faxes
>> even
>> though everything is configured absolutely perfectly. This is not my
>> opinion
>> but the word right from ifax (hylafax) and VSI.
>>
>> I had a lightly loaded gigabit network and only about 8 modems on a 32
>> port
>> digi (or a 16 port equinox for a while). Nics, switch, and digi were all
>> pretty over specced for the dribble of traffic 8 14.4kb modems can
>> deliver.
>> It _mostly_ worked ok. I don't do that any more though.
>>
>> --
>> Brian K. White brian@aljex.com http://www.myspace.com/KEYofR
>> +++++[>+++[>+++++>+++++++<<-]<-]>>+.>.+++++.+++++++.-.[>+<---]>++.
>> filePro BBx Linux SCO FreeBSD #callahans Satriani Filk!
>>
>>
>> How about if I create a "VIRTUAL Serial Port" and then use that one
>> instead
>> ? Is there such thing on SCO Unix ?
>
> What did I just say?
> Thats exactly what I just said the drivers for most such devices provide.
>
> I looks and smells just like a serial port, so, from the software's point
> of view it thinks it's fine.
>
> But that doesn't mean it will actually _work_ well, even though the
> virtual port driver is perfectly robust.
>
> The problem has to do with timing. The fax protocol requires things to
> happen within specific windows of time, and tcp/ip does not garantee that
> any given packet will get delivered within any specific window of time.
>
> Confusingly, on most reasonable lan's it'll actually work ok mostly, but
> even on an over-spec'd lan, tcp/ip just plain doesn't make promises about
> how long a given packet will take to get delivered. That means sometimes
> the fax protocol will break no matter what. Even on a lightly loaded lan
> there are spikes and bursts of other traffic, and those will cause your
> virtual port traffic to incur little pauses, a packet may take 300 ms to
> get delivered instead of .01 ms, and the fax that was in progress fails
> because the handshaking protocol broke because the server needed to
> acknowledge the next phase within 50ms and it took 10 ms to actually do
> the work and then the virtual port took another 300 ms to react to a
> command because the tcp/ip packet that delivered the command took that
> long to get to the serial device server.
>
> If you had a switch that allows you to set QoS levels then you could give
> traffic on the tcp port that the virtual serial driver uses higher
> priority, like what you do for voip. That would probably reduce the
> occurance of delayed commands significantly.
>
> And if you use only fax class 2 modems then since they do most of the fax
> protocol in the modem hardware, that will probably also help to ensure it
> works even more often since it would reduce the number of timing-critical
> commands between the server and the modem.
>
> But it still can never be 100% that way because tcp/ip just plain does not
> promise that anything ever will happen either instantly nor even within
> any specific time, whereas the fax protocol does require and promise that
> various things happen within various times.
>
> --
> Brian K. White brian@aljex.com http://www.myspace.com/KEYofR
> +++++[>+++[>+++++>+++++++<<-]<-]>>+.>.+++++.+++++++.-.[>+<---]>++.
> filePro BBx Linux SCO FreeBSD #callahans Satriani Filk!
>
> I did it!!
>
> I compiled this code :
> ftp://ftp.lantronix.com/priv/svr_tty/svr_tty-README.txt
>
> created a config file,
>
> runned the daemon
>
> and fax is working!!!!!
>
> the only thing is that now ssh can't create ptyp ports or some strange
> thing
> that I thing is related to this program that locks a device.
>
>

well , what can I say, you were right from the beggining, but I tried, Fax
is sent with no problems, but the other side gets a fax that it's fine on
some rows and them fades on other rows and so on :P

So I'll keep tweaking it or getting one of those class 2 modems.

thanks.