When i run the program. Error: network is unreachable

[KMS07]

from mininet.net import Mininet
from mininet.node import Host, Node
from mininet.cli import CLI
from mininet.link import TCLink

def ipv6_to_ipv4_tunnel():
    net = Mininet()

    # IPv6 hosts
    h1 = net.addHost('h1', ip6='2001:db8:1::1/64', ipv6_default=True)
    h2 = net.addHost('h2', ip6='2001:db8:1::2/64', ipv6_default=True)

    # IPv4 host
    h3 = net.addHost('h3', ip='192.168.1.10/24', defaultRoute='via 10.0.0.1')

    # Router for 6to4 tunnel
    r0 = net.addHost('r0', cls=Node, ip='172.16.0.1/30')

    # Links (h1, h2 connect to router with IPv6)
    net.addLink(h1, r0, intfName1='h1-eth0', intfName2='r0-eth0', params1={'ip': '2001:db8:1::1/64'}, params2={'ip': '2001:db8:1::2/64'}, ipv6=True)
    net.addLink(h2, r0, intfName1='h2-eth0', intfName2='r0-eth1', params1={'ip': '2001:db8:1::2/64'}, params2={'ip': '2001:db8:1::1/64'}, ipv6=True)

    # Link between router and h3 (uses IPv4)
    net.addLink(r0, h3, intfName1='r0-eth2', params1={'ip': '172.16.0.1/30'}, params2={'ip': '192.168.1.1/24'}, ipv4=True, cls=TCLink, bw=10)

    # Configure 6to4 tunnel on router
    r0.cmd('ip tunnel add tun0 mode sit remote 192.0.2.1 local 192.0.2.2')
    r0.cmd('ip link set dev tun0 up')
    r0.cmd('ip addr add 2002:beef::1/64 dev tun0')
    r0.cmd('ip -6 route add ::/0 via 2002:c000:201::1 dev tun0')

    net.start()

    # Add default routes for h1 and h2
    h1.cmd('route add default gw 172.16.0.1')
    h2.cmd('route add default gw 172.16.0.1')

    # Test ping between IPv6 and IPv4 hosts
    print(h1.cmd('ping 192.168.1.10 -c 4'))
    print(h3.cmd('ping6 2001:db8:1::1 -c 4'))

    CLI(net)

    net.stop()

if __name__ == '__main__':
    ipv6_to_ipv4_tunnel()

[root-hbx]

If you have ruled out other potential errors such as

• routing configuration
• IPv6 configuration
• subnet masks
• IP Addr conflicts

There is a subtle error to consider:
In Mininet, by default, there may be firewall rules restricting network communication.

You can try disabling the firewall in the script or manually configuring the relevant rules.