Re: ISDN Support
Kevin Traas writes:
> > I have a Motorola Bitsurfr Pro (external). It works fine under Linux;
> > it looks like a modem. (It has a zillion AT commands.)
>
> Thanks for the info. Just a couple of questions.... <grin>
>
> What type of serial port do you have? 16550? How fast are you running the
> serial connection? Higher than 115,200bps? Do you connect at 64K or 128K
> or either?
>
(Apologies if I should have replied privately rather than following up.
I'm not sure if anyone else on this list is interested...)
Until recently I just used the built-in serial ports, which are 16650a
limited to 115000 bps. I have recently bought a Byte Runner card and
am talking to the Bitsurfr at 230400 bps. Have I noticed a big
difference? No. I've started trying some tests, and will switch back
to 115000 and see if it I can measure any difference. There are
typically delays at so many points its hard to get consistent results.
Subjectively (very!) 2 channels are faster than 1, but not twice as
fast.
When I connect to work I always use 2 channels (if I can, sometimes it
only connects with 1; I'm not sure why). Since when connecting to my
ISP I have to pay per-channel per-time I often connect with just 1
channel. Since I have a static address and ISDN connect time is quite
fast compared with an analog I can disconnect and reconnect
differently (e.g. to download a large file I might switch to 2-channel
operation). My connect file sees if a specific file exists, and based
on that connects with 1 or 2 channels.
>From what I have read, an ISDN router is a much nicer route to go,
but costs more; at least 50% more and up (way up).
The Linux Journal usually has an ad for an internal ISDN board
with drivers for Linux; Spellcaster - http://spellcast.com .
> Canada probably has a National ISDN protocol of it's own....
No, I don't think so. I live in Canada and my Bitsurfr is working!
Actually, there is one model of Bitsurfr for Canada/US, and another
for elsewhere (or is it just Europe? I'm not sure).
> One thing I'm interested in is configuring things so that I can
> establish a 1 or 2 B channel connection on demand. My ISP supports
> Multilink PPP; therefore, I'd like to set things up so that if I
> know I'm going to be needing all the bandwidth I can get, I'll
> establish the connection using the two B channels.
I think many routers can change 1 or 2 operations on the fly, but I'm
not sure. An ISDN-card might let you (especially if you had the
source to the driver!!!).
> (It would be great if the Linux box could be set to timeout after a
> period of bandwidth "saturation", drop the single B channel
> connection, and then reconnect using both B channels....)
You might be able to hack diald to do this. However, if your ISP
assigns you a dynamic IP address you might run into problems. With a
static IP address you can drop the connection and call back (within a
limited time) and still talk to the telnet or ftp session. With a
dynamic address the other end would think you were a different person
and so you'd lose your connection. I think.
Richard.
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