Network (LAN) 'lost'

[Uwe Dippel <udippel@uniten.edu.my>]

This morning, at boot, suddenly no LAN. The boot screen already had
some SIOCSIF errors. Solaris booted properly, with LAN.

In a nutshell, eth0 suddenly migrated to eth2, as one and only eth device.

Details:

This is what I get from dmesg:
...
ACPI: Processor [CPU1] (supports 16 throttling states)
8139cp: 10/100 PCI Ethernet driver v1.2 (Mar 22, 2004)
8139cp 0000:00:09.0: This (id 10ec:8139 rev 10) is not an 8139C+ compatible chip
8139cp 0000:00:09.0: Try the "8139too" driver instead.
8139too Fast Ethernet driver 0.9.27
ACPI: PCI Interrupt 0000:00:09.0[A] -> GSI 18 (level, low) -> IRQ 169
eth0: RealTek RTL8139 at 0xd800, 00:02:44:90:97:27, IRQ 169
eth0:  Identified 8139 chip type 'RTL-8100B/8139D'
Uniform Multi-Platform E-IDE driver Revision: 7.00alpha2
...

And there is no other eth:
$ dmesg | grep eth
eth0: RealTek RTL8139 at 0xd800, 00:02:44:90:97:27, IRQ 169
eth0:  Identified 8139 chip type 'RTL-8100B/8139D'
$

ifconfig says
# ifconfig
lo        Link encap:Local Loopback
         inet addr:127.0.0.1  Mask:255.0.0.0
         inet6 addr: ::1/128 Scope:Host
         UP LOOPBACK RUNNING  MTU:16436  Metric:1
         RX packets:12 errors:0 dropped:0 overruns:0 frame:0
         TX packets:12 errors:0 dropped:0 overruns:0 carrier:0
         collisions:0 txqueuelen:0
         RX bytes:600 (600.0 b)  TX bytes:600 (600.0 b)
#

ifconfig does not 'up' eth0:
# ifconfig eth0 up
eth0: ERROR while getting interface flags: No such device
#

But it is in there:
# lspci -v
...
00:09.0 Ethernet controller: Realtek Semiconductor Co., Ltd.
RTL-8139/8139C/8139C+ (rev 10)
       Subsystem: Realtek Semiconductor Co., Ltd. RT8139
       Flags: bus master, medium devsel, latency 64, IRQ 169
       I/O ports at d800 [size=256]
       Memory at febff400 (32-bit, non-prefetchable) [size=256]
       Capabilities: [50] Power Management version 2

Only "man ifconfig" gave me an idea:
# ifconfig -a
eth2      Link encap:Ethernet  HWaddr 00:02:44:90:97:27
         BROADCAST MULTICAST  MTU:1500  Metric:1
         RX packets:0 errors:0 dropped:0 overruns:0 frame:0
         TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
         collisions:0 txqueuelen:1000
         RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)
         Interrupt:169 Base address:0xd800

lo        Link encap:Local Loopback
         inet addr:127.0.0.1  Mask:255.0.0.0
         inet6 addr: ::1/128 Scope:Host
         UP LOOPBACK RUNNING  MTU:16436  Metric:1
         RX packets:12 errors:0 dropped:0 overruns:0 frame:0
         TX packets:12 errors:0 dropped:0 overruns:0 carrier:0
         collisions:0 txqueuelen:0
         RX bytes:600 (600.0 b)  TX bytes:600 (600.0 b)

sit0      Link encap:IPv6-in-IPv4
         NOARP  MTU:1480  Metric:1
         RX packets:0 errors:0 dropped:0 overruns:0 frame:0
         TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
         collisions:0 txqueuelen:0
         RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)
#

And it does work !:
# dhclient eth2
Internet Software Consortium DHCP Client 2.0pl5
Copyright 1995, 1996, 1997, 1998, 1999 The Internet Software Consortium.
All rights reserved.

Please contribute if you find this software useful.
For info, please visit http://www.isc.org/dhcp-contrib.html

sit0: unknown hardware address type 776
sit0: unknown hardware address type 776
Listening on LPF/eth2/00:02:44:90:97:27
Sending on   LPF/eth2/00:02:44:90:97:27
Sending on   Socket/fallback/fallback-net
DHCPREQUEST on eth2 to 255.255.255.255 port 67
DHCPACK from 192.168.116.200
bound to 192.168.116.101 -- renewal in 432000 seconds.


Now I ask myself WHY !?
How can a properly working system suddenly end up with a strange eth2
instead of eth0 ?
How does an eth0 recognised in dmesg at boot migrate to eth2; on its own ?
Is this a bug ?


Uwe