Multiple modems configuration in Linux

Hi All,

Just want to seek for any recommendations for using multiple modem
configuration in Linux (currently using Redhat 7.2, may consider migrarte to
9.0). I'm going to install 4 modem lines connected to the Linux system
(using the vgetty package on a voice application). I'm thinking about the
following different possibilities:

1. Use the 2 com ports on the PC to connect to 2 external modems and add 2
internal modems (I believe most modems can be configured as COM3 and COM4).

2. Buy a port extender card (which can have 2 upto 8 more COM. ports), then
connect all the COM ports to external modems.

3. Buy a multiple modem card (some cards can have 4 to 8 modems on one
single card).

4. Buy 4 different internal modem cards (I'm not sure if its possible to use
them as COM1 to COM4 ?)

5. Or any other combination ???


Could anybody share any experience? What types of modems cards (especially
for multiport modem card) or extender card are recommended, since I want to
make sure that the Linux and vgetty driver can support them. Thanks in
advance.

Rgds,

K.Lam

[vittorio]

if you want to use more than two modems i think that you must buy an
apposite hardware.
i know that you can't use com1 and com3 and com2 and com4 together so even
with 4 com ports you can use only two ports at same time. this because
com1/3 shares the same irq4 and com2/4 shares the same irq3.

there is an hardware that conncet 8/16 modem's com ports to one pc's com
port.

You can use different modems with usb!

bye

<klam@vcn.bc.ca> ha scritto nel messaggio news:3f66b338$2@shknews01...

> Hi All,
>
> Just want to seek for any recommendations for using multiple modem
> configuration in Linux (currently using Redhat 7.2, may consider migrarte

to

> 9.0). I'm going to install 4 modem lines connected to the Linux system
> (using the vgetty package on a voice application). I'm thinking about the
> following different possibilities:
>
> 1. Use the 2 com ports on the PC to connect to 2 external modems and add 2
> internal modems (I believe most modems can be configured as COM3 and

COM4).

>
> 2. Buy a port extender card (which can have 2 upto 8 more COM. ports),

then

> connect all the COM ports to external modems.
>
> 3. Buy a multiple modem card (some cards can have 4 to 8 modems on one
> single card).
>
> 4. Buy 4 different internal modem cards (I'm not sure if its possible to

use

> them as COM1 to COM4 ?)
>
> 5. Or any other combination ???
>
>
> Could anybody share any experience? What types of modems cards (especially
> for multiport modem card) or extender card are recommended, since I want

to

> make sure that the Linux and vgetty driver can support them. Thanks in
> advance.
>
> Rgds,
>
> K.Lam
>
>
>

[Captain Dondo]

On Tue, 16 Sep 2003 15:05:16 +0800, kla wrote:

> Hi All,
>
> Just want to seek for any recommendations for using multiple modem
> configuration in Linux (currently using Redhat 7.2, may consider migrarte to
> 9.0). I'm going to install 4 modem lines connected to the Linux system
> (using the vgetty package on a voice application). I'm thinking about the
> following different possibilities:
>
> 1. Use the 2 com ports on the PC to connect to 2 external modems and add 2
> internal modems (I believe most modems can be configured as COM3 and COM4).
>
> 2. Buy a port extender card (which can have 2 upto 8 more COM. ports), then
> connect all the COM ports to external modems.
>
> 3. Buy a multiple modem card (some cards can have 4 to 8 modems on one
> single card).
>
> 4. Buy 4 different internal modem cards (I'm not sure if its possible to use
> them as COM1 to COM4 ?)
>
> 5. Or any other combination ???
>
>
> Could anybody share any experience? What types of modems cards (especially
> for multiport modem card) or extender card are recommended, since I want to
> make sure that the Linux and vgetty driver can support them. Thanks in
> advance.
>
> Rgds,
>
> K.Lam

You definitely want to buy an intelligent modem card, with all the modems
you need on it.

There are multiple advantages to this:

1. You typically use only one interrupt, not a bunch.
2. The intelligent card has an on-board CPU to handle all of the
comm-stuff so your CPU doesn't have to.
3. The quality of the intelligent cards is typically much higher than some
of the cheap modems around (and if you buy high quality modems, you'll pay
as much.

I used to use Digi quite a bit, but they seem to have run into some
trouble with support. Eicon makes great products, and I'd recommend them
with linux. They actively support linux; there are both binary and
open-source drivers available.

-Dondo

[Nico Kadel-Garcia]

[email]klam@vcn.bc.ca[/email] wrote:

> Hi All,
>
> Just want to seek for any recommendations for using multiple modem
> configuration in Linux (currently using Redhat 7.2, may consider migrarte to
> 9.0). I'm going to install 4 modem lines connected to the Linux system
> (using the vgetty package on a voice application). I'm thinking about the
> following different possibilities:

I'd use HylaFAX, at [url]www.hylafax.org[/url]. The modem configurations are better
maintained and so far as I know, it gets used more in industrial grade
environments.

> 1. Use the 2 com ports on the PC to connect to 2 external modems and add 2
> internal modems (I believe most modems can be configured as COM3 and COM4).

That won't work. COM3 and COM4 use the same IRQ's as COM1 and COM2, via
an extremely confusing and often irritating signal splitting scheme. You
need another serial card, perhaps a Rocketport 8-port serial card, or
another couple of PCI modems. I'd actually recommend grabbing the
Rocketport and using similar if not identical external modems, to avoid
having to deal with those !@#$ Winmodems.

> 2. Buy a port extender card (which can have 2 upto 8 more COM. ports), then
> connect all the COM ports to external modems.

This is pretty well guaranteed to work.

> 3. Buy a multiple modem card (some cards can have 4 to 8 modems on one
> single card).

Yeah, although these are often quite expensive.

> 4. Buy 4 different internal modem cards (I'm not sure if its possible to use
> them as COM1 to COM4 ?)

Maybe, their IRQ's will be assigned depending on their jumpers, any PNP
settings, etc. They'll show up as /dev/tty* devices on a modern Linux
kernel.

> 5. Or any other combination ???

Two el cheap throwaway computers both running HylaFAX or vgetty with a
pair of modems each. I've done this, rather than buy hardware.

> Could anybody share any experience? What types of modems cards (especially
> for multiport modem card) or extender card are recommended, since I want to
> make sure that the Linux and vgetty driver can support them. Thanks in
> advance.

Rocketport has a very, very good name. I've used the ECPA expanders and
not been real thrilled with them: whoever packaged their kernel driver
tools should have been shot.

[mjt]

[email]klam@vcn.bc.ca[/email] wrote:

> 2. Buy a port extender card (which can have 2 upto 8 more COM. ports),
> then connect all the COM ports to external modems.
>
> 3. Buy a multiple modem card (some cards can have 4 to 8 modems on one
> single card).

.... either one of those would do, except i'd go for (2) since
this would allow you complete control over each of the modems.
and be sure to get REAL H/W modems.

many years ago, i wrote multi-line BBS software and used the
digiboard boards: [url]http://www.digi.com[/url]
..
--
/// Michael J. Tobler: motorcyclist, surfer, skydiver, \\\
\\\ and author: "Inside Linux", "C++ HowTo", "C++ Unleashed" ///
\\\ [url]http://pages.sbcglobal.net/mtobler/mjt_linux_page.html[/url] ///
"Outside of a dog, a book is a man's best friend: and inside a
dog, it's too dark to read." -- Groucho Marx

In article <3f66b338$2@shknews01>, <klam@vcn.bc.ca> wrote:

>
>
>Hi All,
>
>Just want to seek for any recommendations for using multiple modem
>configuration in Linux (currently using Redhat 7.2, may consider migrarte to
>9.0). I'm going to install 4 modem lines connected to the Linux system
>(using the vgetty package on a voice application). I'm thinking about the
>following different possibilities:
>
>1. Use the 2 com ports on the PC to connect to 2 external modems and add 2
>internal modems (I believe most modems can be configured as COM3 and COM4).
>
>2. Buy a port extender card (which can have 2 upto 8 more COM. ports), then
>connect all the COM ports to external modems.
>
>3. Buy a multiple modem card (some cards can have 4 to 8 modems on one
>single card).
>
>4. Buy 4 different internal modem cards (I'm not sure if its possible to use
>them as COM1 to COM4 ?)
>
>5. Or any other combination ???
>
>
>Could anybody share any experience? What types of modems cards (especially
>for multiport modem card) or extender card are recommended, since I want to
>make sure that the Linux and vgetty driver can support them. Thanks in
>advance.
>
>Rgds,
>
>K.Lam
>
>
>

i have used cyclades multiple serial port cards successfully
this requires external modems

i dont like internal modems since sometimes they hang in such
a manner as to require a cold reboot of the machine
whereas an external modem can be powercycled with its own powerswitch

sidd