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RTFM · Troubleshooting

Interfaces missing

eth0 vanished, or the interface has another name entirely: driver loading, renaming surprises, bridges, and virtual switches explained.

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Distinguish absent from renamed

An interface that renamed itself looks identical to one that never existed. List everything the kernel knows about before concluding hardware failure.

What does the kernel actually see?
ip -o link show
ls /sys/class/net/

dmesg | grep -iE 'eth|enp|firmware|link up'

Driver did not load

If /sys/class/net contains only lo, the NIC driver either failed to load or lacks firmware. The dmesg excerpt names both precisely.

  1. 1. Identify the NIC

    lspci gives vendor:device IDs for the controller.

  2. 2. Check firmware messages

    dmesg | grep -i firmware — 'failed to load' lines name the required file.

  3. 3. Install matching firmware/drivers

    apk search finds the relevant package; the Bootstrap guide explains kernel module selection for custom kernels.

  4. 4. Or modprobe directly

    modprobe <drivername> loads immediately to prove the diagnosis without rebooting.

Bridges, OVS and VLAN devices

Missing bridge or OVS ports mean the datapath was never created. Verify existence first:

Virtual device inventory
ovs-vsctl show               # OVS datapath present?
ovs-vsctl list-br
ip link show type bridge

Prove it works: predictable interface mapping

you can state which physical port corresponds to which interface name, documented in /etc/network.d comments, so next week's failure starts ahead.

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