Subject: NetBSD and cable modems
To: None <>
From: Matthias Scheler <>
List: tech-net
Date: 12/30/1998 21:18:48

is anyone successfully using a NetBSD system connected to a cable modem via
ethernet? My scenario looks like this:

NetBSD Box
SSDL cable modem as bridge (768KBit/sec)
               leased line
SSDL cable modem as bridge
    |                           |
Linux Box                     Router

When I connected the NetBSD box with an SMC 8434 (dual DEC 21040 board,
de driver) it complained about transmit underflows quite oftern and
freezed after a while (NetBSD 1.3.2: 14 days, NetBSD 1.3.3: 12 hours,
NetBSD 1.3I: 3 days).

Today I replaced the SMC 8434 with a D-Link DFE500TX and a 3Com 3c905
and connected the cable modem to the 905. Now the machine doesn't
freeze but after a while the ethernet with the cable modem is dead
and I have to do a "ifconfig ex0 down" and "ifconfig ex0 up" to
revive it.

Is it possible that NetBSD's ethernet engine has severe problems with
transmitting large amounts of data to slow partners? Or are both the
"de" and the "ex" driver broken?

Matthias Scheler