Mininet provides a convenient way for building multi-device linear topologies with the
--topo linear option:

 $ sudo mn --topo linear,2 --mac --controller remote --switch ovsk
 ...
 mininet> links
 h1-eth0<->s1-eth1 (OK OK)
 h2-eth0<->s2-eth1 (OK OK)
 s2-eth2<->s1-eth2 (OK OK)

By default, the hosts were assigned the same IP addresses sequentially, similar to a single-switch topology:

 mininet> dump
 <Host h1: h1-eth0:10.0.0.1 pid=29367>
 <Host h2: h2-eth0:10.0.0.2 pid=29375>
 <OVSSwitch s1: lo:127.0.0.1,s1-eth1:None,s1-eth2:None pid=29383>
 <OVSSwitch s2: lo:127.0.0.1,s2-eth1:None,s2-eth2:None pid=29386>
 <RemoteController c0: 127.0.0.1:6633 pid=29361>

We can easily change the IP addresses of the hosts according to our diagram:

 mininet> h1 ip addr del 10.0.0.1/8 dev h1-eth0
 mininet> h1 ip addr add 192.168.1.10/24 dev h1-eth0
 mininet> h2 ip addr del 10.0.0.2/8 dev h2-eth0
 mininet> h2 ip addr add 192.168.2.10/24 dev h2-eth0
 mininet> h1 ip route add default via 192.168.1.1
 mininet> h2 ip route add default via 192.168.2.1

We can verify the configuration as follows:

 mininet> h1 ifconfig | grep inet
 inet addr:192.168.1.10 Bcast:0.0.0.0 Mask:255.255.255.0
 inet6 addr: fe80::200:ff:fe00:1/64 Scope:Link
 inet addr:127.0.0.1 Mask:255.0.0.0
 inet6 addr: ::1/128 Scope:Host
...
 mininet> h2 ifconfig | grep inet
 inet addr:192.168.2.10 Bcast:0.0.0.0 Mask:255.255.255.0
 inet6 addr: fe80::200:ff:fe00:2/64 Scope:Link
 inet addr:127.0.0.1 Mask:255.0.0.0
 inet6 addr: ::1/128 Scope:Host
...
 mininet> h1 route -n
 Kernel IP routing table
 Destination Gateway Genmask Flags Metric Ref Use Iface
 0.0.0.0 192.168.1.1 0.0.0.0 UG 0 0 0 h1-eth0
 192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 h1-eth0
...
 mininet> h2 route -n
 Kernel IP routing table
 Destination Gateway Genmask Flags Metric Ref Use Iface
 0.0.0.0 192.168.2.1 0.0.0.0 UG 0 0 0 h2-eth0
 192.168.2.0 0.0.0.0 255.255.255.0 U 0 0 0 h2-eth0
 mininet>

Great! We've built the topology we needed in less than 5 minutes. Keep these steps handy, as we will start and restart Mininet a few times during our build. Let's take a look at the code that we will be using.