From: Trever Adams <trever_Adams@bigfoot.com>
Subject: 2.3.49 and Tulip (more reports to go with those of others)
Boot machine with network switch off. Start switch. Networking is dead. Can't ping in or out. Cannot telnet or anything else in.
[root@aurora quantumdot]# ifdown eth0
[root@aurora quantumdot]# ifup eth0
SIOCSIFFLAGS: No such device
SIOCADDRT: Network is down
Mine is a netgear with the real DEC chip in it. I hope this helps debug it.