Configure an 802.1Q VLAN on Slackware

1. Goal

Create a tagged interface and verify its traffic without disrupting the main setup.

2. Files and components involved

/etc/rc.d/rc.modules
/sbin/modprobe
/sbin/ip
eth0.20

3. Operational flow

modprobe 8021q
ip link add link eth0 name eth0.20 type vlan id 20
ip addr add address dev eth0.20
ip link set eth0.20 up

4. Operational verification

ip -d link show eth0.20
ip addr show eth0.20
ping VLAN gateway
tcpdump -ni eth0 vlan 20

5. Practical notes

Apply network changes from a local console or with an emergency session ready, so you do not lose SSH access.

Every network change should have a rollback path ready: a second console, KVM access, or a temporary command to remove.

Quick checklist

[ ] Backup or copy of the existing configuration completed
[ ] Files and commands updated as expected
[ ] Local test completed successfully
[ ] Logs or final output verified
[ ] Rollback procedure documented

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