Build the lab yourself

# Needs ./vyos (from the tcpdump-and-vyos lesson's get-vyos.sh). Then: docker compose up -d --build
# Switch and PC commands:  docker compose exec lab sh        (the switch: bridge, tcpdump, ...)
#                          docker compose exec lab ip netns exec pc1 sh
# VyOS console:            docker compose exec -it lab socat -,raw,echo=0,escape=0x1d UNIX-CONNECT:/run/console.sock
name: switching-lab
services:
  lab:
    build:
      context: .
      dockerfile_inline: |
        FROM debian:bookworm-slim
        RUN apt-get update && apt-get install -y --no-install-recommends \
          qemu-system-x86 iproute2 socat procps tcpdump iputils-ping traceroute
        COPY start-switchlab.sh /usr/local/bin/start-switchlab.sh
        CMD ["/usr/local/bin/start-switchlab.sh"]
    hostname: sw1
    privileged: true
    network_mode: none
    volumes: ["./vyos:/vyos:ro"]

• Lines 2–3: How to get a shell on the switch, or on a PC.
• Line 18: No Docker networking at all: every cable is created inside the container.

#!/bin/sh
# Everything in one container, no Docker networking: three PCs as network namespaces, cabled with veth pairs
# to switch ports eth1-eth3, and the VyOS VM's NIC as switch port eth4 (a tap). The switch itself (br0) is
# configured later, so each stage of the lesson can be shown.
set -e
sysctl -qw net.ipv6.conf.all.disable_ipv6=1 net.ipv6.conf.default.disable_ipv6=1
for n in 1 2 3; do
  ip netns add "pc$n"
  ip link add "eth$n" type veth peer name eth0 netns "pc$n"
  ip -n "pc$n" link set eth0 address "02:00:00:00:00:0$n"
  ip netns exec "pc$n" sysctl -qw net.ipv6.conf.all.disable_ipv6=1
  ip -n "pc$n" link set lo up
  ip -n "pc$n" link set eth0 up
  ip link set "eth$n" up
done
ip tuntap add eth4 mode tap
ip link set eth4 up
exec qemu-system-x86_64 -m 1536 -smp 1 -cpu max -accel tcg,thread=multi \
  -uuid 00000000-0000-4000-8000-000000000001 \
  -kernel /vyos/vmlinuz -initrd /vyos/initrd.img \
  -append "boot=live components hostname=vyos username=live nopersistence noautologin nonetworking union=overlay console=ttyS0,115200 net.ifnames=0 biosdevname=0" \
  -cdrom /vyos/vyos.iso -netdev tap,id=n0,ifname=eth4,script=no,downscript=no -device virtio-net-pci,netdev=n0,mac=52:54:00:01:00:01 \
  -display none -serial unix:/run/console.sock,server=on,wait=off -monitor none

• Line 8: Each PC is a network namespace…
• Line 9: …cabled to switch port ethN with a veth pair.
• Line 10: Fixed, readable MAC addresses.
• Lines 16–17: The VyOS VM's NIC becomes switch port eth4.