Build the lab yourself

#!/bin/sh
# The IPv6 lesson: turn IPv6 back on everywhere except where the router's own config does it,
# remove the addresses and routes Docker adds, and start the ISP's DHCPv6 server.
dc() { docker compose -f lab-compose.yaml "$@"; }
x() { dc exec -T "$1" sh -c "$2"; }
on='for f in /proc/sys/net/ipv6/conf/*/disable_ipv6; do echo 0 > $f; done; ip -6 addr flush scope global; ip -6 route flush default 2>/dev/null; true'
for n in isp web staff guest server; do x $n "$on"; done
# The ISP: 2001:db8:f::1 towards customers, 2001:db8:e::1 towards the "internet", and Kea.
x isp 'ip -6 addr add 2001:db8:f::1/64 dev eth0; ip -6 addr add 2001:db8:e::1/64 dev eth1; sysctl -qw net.ipv6.conf.all.forwarding=1; mkdir -p /var/lib/kea /run/kea /var/log/kea'
dc cp isp/kea-dhcp6.conf isp:/etc/kea/kea-dhcp6.conf >/dev/null
dc cp isp/pd-route.sh isp:/etc/kea/pd-route.sh >/dev/null
sleep 3   # let the new link-local addresses finish duplicate address detection first
x isp 'nohup kea-dhcp6 -c /etc/kea/kea-dhcp6.conf > /dev/null 2>&1 &'
# The web server, now on both IPv4 and IPv6.
x web 'ip -6 addr add 2001:db8:e::10/64 dev eth0; ip -6 route add default via 2001:db8:e::1; pkill python3; cd /tmp && nohup python3 -m http.server 80 --bind :: > /tmp/web.log 2>&1 &'

• Lines 6–7: IPv6 back on, and Docker's own addresses and default routes removed.
• Lines 12–13: Kea starts only after the link-local addresses are ready.

// The ISP's DHCPv6 server (Kea): delegates a /56 to each customer router.
{
  "Dhcp6": {
    "interfaces-config": { "interfaces": [ "eth0" ] },
    "lease-database": { "type": "memfile", "persist": true, "name": "/var/lib/kea/kea-leases6.csv" },
    "renew-timer": 900, "rebind-timer": 1800, "preferred-lifetime": 3600, "valid-lifetime": 7200,
    "subnet6": [ {
      "id": 1, "subnet": "2001:db8:f::/64", "interface": "eth0",
      "pd-pools": [ { "prefix": "2001:db8:ab00::", "prefix-len": 48, "delegated-len": 56 } ]
    } ],
    // A real ISP's routers learn the route to each delegated prefix; in the lab, a script adds it.
    "hooks-libraries": [ {
      "library": "libdhcp_run_script.so",
      "parameters": { "name": "/etc/kea/pd-route.sh", "sync": false }
    } ],
    "loggers": [ { "name": "kea-dhcp6", "output-options": [ { "output": "/var/log/kea/kea-dhcp6.log" } ], "severity": "INFO" } ]
  }
}

• Line 9: Delegate a /56 from 2001:db8:ab00::/48 to each customer.
• Lines 12–15: The run_script hook, named without a path, calls the route script for every lease event.

#!/bin/sh
# Kea's run_script hook: route each delegated prefix to the router that asked for it.
[ "$1" = "leases6_committed" ] || exit 0
i=0
while [ "$i" -lt "${LEASES6_SIZE:-0}" ]; do
  eval type=\$LEASES6_AT${i}_TYPE prefix=\$LEASES6_AT${i}_ADDRESS len=\$LEASES6_AT${i}_PREFIX_LEN
  [ "$type" = "IA_PD" ] && ip -6 route replace "$prefix/$len" via "$QUERY6_REMOTE_ADDR" dev eth0
  i=$((i + 1))
done

• Line 3: Only when leases are committed.
• Line 7: Route each delegated prefix to the address the request came from.