sudo mn --topo linear,3 --mac --controller=remote,ip=192.168.56.3,port=6633 --switch ovs,protocols=OpenFlow13

mininet@mininet-vm:~$ sudo mn --topo linear,3 --mac --controller=remote,ip=192.168.56.3,port=6633 --switch ovs,protocols=OpenFlow13
*** Creating network
*** Adding controller
Unable to contact the remote controller at 192.168.56.3:6633
*** Adding hosts:
h1 h2 h3
*** Adding switches:
s1 s2 s3
*** Adding links:
(h1, s1) (h2, s2) (h3, s3) (s2, s1) (s3, s2)
*** Configuring hosts
h1 h2 h3
*** Starting controller
c0
*** Starting 3 switches
s1 s2 s3 ...
*** Starting CLI:
mininet>