Just recently updated my 10yr old hardware to a ryzen-based system, and I was having a bit of difficulty bringing the network up. I admit the last time I couldn't bring up a network was on a 486 machine, so I was/am flying a bit foggy here.

I HAD managed to get it working once, but upon reboot, and re-doing the steps I wrote down, nothing - gone.

What I had discovered:
ifconfig -a shows
eth1 eth2 loopback wlan0 (notice no eth0? I'll honestly admit I didn't notice for 20 min.)

inet1.conf has an entry for eth0

router has the new mac address for one of them (asrock doesnt make it clear which is lan1 or lan2, so its a bit of a guess)

while the loading messages go flying past, igb (which seems to be the network module? or so says a ubuntu page with similar toubles) is grabbing and changing:
igb 0000:04:00.0 eth126: renamed from eth0
igb 0000:04:00.0 eth2: renamed from eth126

Locating and learning the above, i've modified rc.inet1.conf
eth2 to use_dhcp="yes"

hung a bit, failed; moved the cable, tried again it worked.

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So I supposed the question is, WHY, why is igb moving eth0 over to eth126 over to eth2?

Why doesn't it report similarily with the other lan connection (or is it already eth1? I never did check)? Does this have to do with the ioumm grouping thingy I've briefly heard about? Is there a way to prevent or change this rather unexpected behaviour? (eth0 decides it wishes to be eth2!)

Perhaps this is normal? I don't know.

You should check and probably edit /etc/udev/rules.d/70-persistent-net.rules which keeps a record of of network interface addresses and the names (eth0, eth1, ...) which have been assigned to them when they were first discovered. These assignments are looked up and replicated at each boot (maintaining consistency across reboots). My guess is that your .rules file will have eth0 assigned to the interface from your previous mobo, then eth1 & eth2 assigned to interfaces on your new mobo. You can edit the .rules file - remove the eth0 entry, then change the remaining assigments to eth0 & eth1. If you don't know which interface relates to a particular cable socket, trial and error will show whether you assign the names correctly. If it's wrong, swap the names over (and reboot), or just swap the cable to the other socket.

chris

1 members found this post helpful.

Hi,

Or you can remove '/etc/udev/rules.d/70-persistent-net.rules' and then reboot system to generate a new '/etc/udev/rules.d/70-persistent-net.rules' file.

Hope this helps.
Have fun & enjoy!

1 members found this post helpful.

Thank you! Okay, was not aware of the udev rules portion, I will reboot and let it rebuild.

*IF* it doesn't work, I have an additional possible path to track. Started the machine up today, nothing physically changed from last session, and the _other_ lan port suddenly became eth2 and the previous working one was now eth1.

I think I have run into this before (oddly, back on the 486 and 3 same model nics). Polling Order? Will see how udev finds the port(s) after a few restarts.

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It rebuilt the file, shows the correct ports with correct MACs. Thank you!