ISDN with BitSurfr

thoth@purplefrog.com
Tue, 22 Oct 1996 15:50:25 EDT

Well, I bought one of those TC-200-S6-1 cards (16650 UART, 460Kb max DTE) to
use under Linux with my BitSurfr Pro. After a little fiddling I got my
scripts to work again (the fact that the BitSurfr can't autobaud into or out
of 230Kb makes it a hassle. Also, you have to "trick" the Linux kernel into
doing 230Kb because it doesn't yet know about that speed. That bit is easy).

All-in-all, I was able to increase my NetPipes (a raw TCP stream connection)
throughput from 9.1KB/sec to 10KB/sec by moving to the higher DTE. This still
isn't the 14KB/sec FTP times my friend with a pair of Ciscos reports over his
ISDN line.

Maybe the Cisco is doing compression.
Maybe I have some stupid arguments to pppd.
Maybe the BitSurfr isn't terribly good at saturating either link.
Maybe the PortMaster isn't terribly good at saturating either link.
Maybe that's near the theoretical limit of an ISDN connection after you
factor in the TCP overhead.
Maybe I have exposed inefficiencies in Linux's software.
Maybe BellSouth's switch isn't really giving me 128Kb.
Maybe "dd" isn't efficient at spewing/slurping data (but it's good for
counting out bytes from /dev/zeros).
Maybe my cat is chewing on grass right now.

I don't know. I'm disappointed, but it was only $33 after shipping, so I'm
not jumping off any bridges (not that there's anything high enough in Florida
to jump off and kill yourself).

My BitSurfr is still rock-solid with ROM J. I think it's been up for ~4 days
straight now. The only reason it disconnects at all is I'm either running
diald, or I reboot the machine to play Warcraft II.