(mininet) Topology with 2 hosts of different subnets, 2 switches, and a router

Question

I want to write a python code to create the following network: h1 with ip=10.0.1.1\24, linked to switch s1, s1 linked to router r0, r0 linked to switch s2, s2 linked to h2 with ip=10.0.2.1\24 and I must not use a controller!

this is the code I used to create the net:

#!/usr/bin/env python2

from mininet.net import Mininet
from mininet.node import Node
from mininet.topo import Topo
from mininet.cli import CLI
from mininet.log import setLogLevel

class LinuxRouter(Node):
    def config(self, **params):
        super(LinuxRouter, self).config(**params)
        self.cmd('sysctl net.ipv4.ip_forward=1')

    def terminate(self):
        self.cmd('sysctl net.ipv4.ip_forward=0')
        super(LinuxRouter, self).terminate()

class CustomTopology(Topo):
    def build(self):
        # Create hosts
        h1 = self.addHost('h1', ip='10.0.1.1/24')
        h2 = self.addHost('h2', ip='10.0.2.1/24')

        # Create switches
        s1 = self.addSwitch('s1')
        s2 = self.addSwitch('s2')

        # Create router
        r0 = self.addNode('r0', cls=LinuxRouter)

        # Add links
        self.addLink(h1, s1, intfName1='h1-eth0', intfName2='s1-eth1')
        self.addLink(s1, r0, intfName1='s1-eth2', intfName2='r0-eth1', params2={'ip': '10.0.1.254/24'})
        self.addLink(r0, s2, intfName1='r0-eth2', intfName2='s2-eth1', params2={'ip': '10.0.2.254/24'})
        self.addLink(s2, h2, intfName1='s2-eth2', intfName2='h2-eth0')

if __name__ == '__main__':
    setLogLevel('info')
    topo = CustomTopology()
    net = Mininet(topo=topo, controller=None)  # Remove the controller
    net.start()
    CLI(net)
    net.stop()

and I am adding flows as follows:

#!/usr/bin/env python3

import subprocess

def run_command(command):
    """
    Run a shell command and handle errors.
    """
    result = subprocess.run(command, shell=True, capture_output=True, text=True)
    if result.returncode != 0:
        print(f"Error running command: {command}\n{result.stderr}")
    else:
        print(f"Command succeeded: {command}\n{result.stdout}")

def push_flows():
    # Flow entries for switch s1
    run_command('sudo ovs-ofctl add-flow s1 priority=100,arp,actions=output:NORMAL')
    run_command('sudo ovs-ofctl add-flow s1 priority=100,ip,actions=output:NORMAL')
    run_command('sudo ovs-ofctl add-flow s1 priority=100,icmp,actions=output:NORMAL')

    # Flow entries for switch s2
    run_command('sudo ovs-ofctl add-flow s2 priority=100,arp,actions=output:NORMAL')
    run_command('sudo ovs-ofctl add-flow s2 priority=100,ip,actions=output:NORMAL')
    run_command('sudo ovs-ofctl add-flow s2 priority=100,icmp,actions=output:NORMAL')



if __name__ == '__main__':
    push_flows()

But it gives me this when I try to ping h2 from h1: mininet> h1 ping h2 -c 10 ping: connect: Network is unreachable

How can I fix it?