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Old 07-02-2002, 11:52 AM   #1
Moeses
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Question USB Modem with Red Hat Linux


We are using Red Hat Linux as our os, on some of our cpu's. I we are using an internal modem as of right now, however they are not very polite and stomp on the line whenever it is being used. We tried to use another MultiTech modem in the Linux box and we could not get Linux to recognize it. Just to make sure the card was good, we put it in a Windows pc and was picked up and installed with no problem, so here is the dilema. We are contemplating going to an external USB Modem that is super polite and super fast. I was just curious if anyone has had experience with Red Hat Linux and external modems. Are there any foreseeable problems? Will Linux recognize the external modem easily? Any of these insights and any other would be strongly appreciated.
 
Old 07-02-2002, 04:59 PM   #2
DavidPhillips
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The best thing to do is get an external hardware modem that plugs into the com port.

Linux will access the com port directly so the modem will work. I would not use USB. USB depends on newer drivers and the drivers for any given USB modem may not work as well as the com port modem.

The com port is faster than the max speed you will ever get on a modem, so there is no speed difference.


I use US Robotics Fax Modems
 
Old 07-02-2002, 09:31 PM   #3
zLinuxz
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I totaly agree with DabidPhillips, the best thing you can do is NOT get a USB modem...get a serial external modem, I have one and it runs like thunder! I have connected to v.90 networks...damn, downloading rates of up to 22k/sec!!, and USB is damn slow too and a pain in the butt, so be smart ,don't get USB,

zLinuxz
 
Old 07-02-2002, 10:49 PM   #4
DavidPhillips
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also you can boost your com port settings with setserial

check your settings like this

setserial -ga /dev/ttyS0
/dev/ttyS0, Line 0, UART: 16550A, Port: 0x03f8, IRQ: 4
Baud_base: 115200, close_delay: 50, divisor: 0
closing_wait: 3000
Flags: spd_shi skip_test low_latency

it will probably default to the best settings with autoconfig, but if yours has spd_normal and you want to try a faster speed try this

setserial /dev/ttyS0 spd_shi

a 56k modem is capable of a port speed over 115200 so setting spd_shi will set it to 230400


baud_base baud_base
This option sets the base baud rate, which is the
clock frequency divided by 16. Normally this value
is 115200, which is also the fastest baud rate
which the UART can support.

spd_hi Use 57.6kb when the application requests 38.4kb.
This parameter may be specified by a non-privileged
user.

spd_vhi
Use 115kb when the application requests 38.4kb.
This parameter may be specified by a non-privileged
user.

spd_shi
Use 230kb when the application requests 38.4kb.
This parameter may be specified by a non-privileged
user.


if you have a decent cpu this may be worth a try


low_latency
Minimize the receive latency of the serial device
at the cost of greater CPU utilization. (Normally
there is an average of 5-10ms latency before char-
acters are handed off to the line discpline to min-
imize overhead.) This is off by default, but cer-
tain real-time applications may find this useful.

^low_latency
Optimize for efficient CPU processing of serial
characters at the cost of paying an average of
5-10ms of latency before the characters are pro-
cessed. This is the default.
 
Old 07-03-2002, 10:11 AM   #5
zLinuxz
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ohhhh, very interesting.

zLinuxz
 
Old 07-03-2002, 08:35 PM   #6
steved123
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hardware

I'm using a actiontech call waiting usb modem. It works for 2 linux boxes via and sis chipsets (for athalon). I have a belkin usb switch so I don't have to keep moving the plug. I just got a call from a telemarketer and sucessfully answered, hung up and remained connected to my isp.
make sure you get a hardware usb modem. Zoom sells 2 usb modems. one is a windows modem so check at linmodems.org
for the usb list so you get the right one. It is on one of the links to modem lists.
 
Old 07-03-2002, 11:08 PM   #7
zLinuxz
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you can do all that and more with a com modem or a serial modem, and you don't have to worry about dumb usb configuration.

Be practical,

zLinuxz
 
  


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