eth0 and eth1 switch places on reboot?

slayer17 · 12-07-2005, 11:13 AM

Had a network problem the other night and had to reboot the server. Upon starting the nic cards reversed order. The eth0 information was switch with the eth1 information creating tons of confusion. The mac address was hard coded in the /etc/syconfig/ area but hwconf seems to have chanced. Any idea why the cards would have switched? Can anyone point me in the right direction?

peter_robb · 12-12-2005, 03:55 PM

The first card to load it's driver gets to be eth0..

It can be controlled by delaying setting up eth1 until eth0 settles,
however there are several factors in play here.
acpi is the first to detect the card, then hotplug then your /etc/modules file then the /etc/init.d scripts.

Usually, the rc.d scripts and ifup allow you to specify a pre-up script/command, which you could use to load the respective eth modules, if they aren't autoloading already. Your distro will have a specific way of doing this..

But if all else fails, compile into the kernel the driver for the card you want to be eth0. This ensures it will get loaded by the acpi system before any other scripts run.

slayer17 · 12-12-2005, 04:18 PM

The problem is that the cards are the same and the system has been rebooted several times before without the cards switching. Now all of the suddon the cards switch and great a networking nightmare. I have never had cards switch at this point.

peter_robb · 12-12-2005, 04:44 PM

Take a close look at the boot logs.
There is a lot of detailed info about hardware being detected and modules loading. You may get some more sense comparing a pre and post problem log.

Usually nothing changes until something changes..

pIscIs · 12-13-2005, 03:39 PM

i think that your net cards has a different module name. so if i correct, you can assign your card1 to eth0 with alias command. so in modules.conf add: alias eth0 module_name

peter_robb · 12-14-2005, 09:31 AM

All that will do is load the particular module regardless of the type of NIC found as eth0..

slayer17 · 12-14-2005, 10:04 AM

I will have to moniter it from this point forward. I just started working for this company and don't know anything about this systems. They had no linux admin until about 2 weeks ago... me. I was just concerned because I have never seen cards set to macs chance name locations without being told to do so. I am starting to believe that someone set it up that way and upon boot it did it. No way to tell because the logs don't show anything but normal steps.

peter_robb · 12-14-2005, 03:14 PM

dmesg or your boot log will show which card it believes it found first..

eg.
PCI: Found IRQ 11 for device 00:0d.0
eth0: RealTek RTL8139 at 0xd0822f00, 00:90:0b:04:47:91, IRQ 11
eth0: Identified 8139 chip type 'RTL-8100B/8139D'

shows the first found card was in pci slot 00:0d.0

or if you've got acpi working..
ACPI: PCI Interrupt 0000:01:00.0[A] -> Link [LNKA] -> GSI 11 (level, low) -> IRQ 11
e100: eth0: e100_probe: addr 0xe6000000, irq 11, MAC addr 00:A0:C9:4B:B5:79

shows the first found card was in pci slot 0000:01:00.0

There's no reason for this to change unless the BIOS is changed.

winsnomore · 12-14-2005, 08:33 PM

slayer17 ... there is no magic .. it was always like this.
It has to do with what boot/install did with module.conf does ..
edit the file and live happy thereafter.

Peter_Robb is correct, but the only twist I am suggesting is that it was always like this .. has happend to me a zillion times ... mostly with Suse, knoppix/Mepis never caused the same grief on the same hardware