On Thu, Jun 29, 2000 at 10:54:41PM +0300, Andrei V.Loukinykh wrote:
> Hello!
> By the way, to this question.
> How do multiport cards compare with usual serial ports?
> What system requirements do they need to work exactly as serial ports?
> I'm using DigiBoard - 16 ports , and I can say now - it works at least
> 20-30 % worse
> then standard serial port ( I just do file transfer (ppp-connection) and
> watch periodical congestions,
> interrupts in transfer - and it is not a bad line - it's a rule.)
Wow! That sucks!
I've run several ISDN lines (230,400 baud on the DTE) on a single
Computone board and rack up less than 0.001% RX-ERR on the PPP interfaces.
Lots of times I see no error accumulation on the Computone interfaces.
It's about 10x better than what I see on the bit-banger boards based on
what I see on the "netstat -ni" results. I've got some "double clocking"
bit-banger boards with 16550A UARTS overclocked so 115,200 is really
230,400 for the ISDN TAs. Comparisons are referenced to those double
clocked boards booking out at 230,400.
I've seen sustained throughput rates downloading compressed files
that hit anywhere from 14 K to 16 K Bytes per second (2 - 64Kbit channels
should yield 16 K Bytes per second max. Usually a little less due to
overhead, sometimes a little more from compression).
Just for some points on the curve... I've had the Computone ISA
boards running in a little 486/33 gateway and later in a K6/120 with no
problem. Currently, I'm using the PCI boards in K6/300 systems. Don't
mix ISA and PCI boards in the same box. I don't think we worked out
all the glitches in that combination. You can put up to 4 ISA or 4 PCI
cards in the same box, however. I generally don't run with more than
one interface and that supports up to 64 ports (4 expansion modules with
16 ports on each).
Never saw a hickup from the Computone boards. I use to use
Motorola Bitsurfer ProEZ terminal adapters which would go brain damaged
from time to time and would have to be power cycled to recover (or
disconnected from the ISDN line - power cycling was easier). I had to
put the Bitsurfers on X10 controllers so I could shut them off and restart
them remotely (through an alternate link) when they died. Now I'm using
3Com ISDN Pro TAs (lightening took out the Bitsurfers - may they rest in
peace) and I haven't had them die even once.
We had some digi boards (since retired) at the office but they were
never used on anything faster than 38.4 so throughput was never an issue
as far as I could tell.
Computone boards can be a bit pricey (especially if you get them
straight from Computone) but they can be obtained at a reasonable discount
from places like CDW. My experience has been that the Computone II boards
are rock solid high performance boards. The earlier Computone boards
(~ 10 years ago) sucked - Even they admit the earlier model was an
embarassment). Those earlier boards are not supported in any way shape
or form by the Linux Computone drivers, and won't be.
Another point on the curve... USB is another alternative that
some might consider for multiple serial ports or adapters. It might
work or it might not. It should work but has gotchas.
My 3Com ISDN Pro TAs supports USB and the Linux USB drivers support
those devices. So I tried that as well. It didn't last long. It might
survive one modem at 128Kbaud but four ISDN lines demonstrated that USB
wasn't quite up to prime time in the higher capacity or throughput
arenas. One active USB TA would run fine, but stall every once in a
while under heavy load. Two active TAs (routing between the two links)
would not survive and the RX-ERR rates where as high as .1% to even 1% at
times. Three active links at 128K just wouldn't cut it at all and the error
rates were through the roof. Never got to four...
> I use 2.2.16 , pentium ~180 (centaur chip) Mhz, 64k RAM and standard driver
> for Digi, compiled
> in.
> Regards,
> Andrei
Disclaimer: I DON'T work for Computone, but I helped do a lot of
the driver integration and getting the drivers into the main kernel sources,
so I am a bit biased. I got involved with them because earlier boards
sucked and the add on driver process was a pain. Now the boards don't
suck and they don't require additional kernel patching. :-)
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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