Intra-cluster communication between two ONOS instances uses the communication port : 9876

Intra-cluster communication happens on port 9876 and if you check the communication. It is only TCP packets with a data field communicating binary data.

mininet> h1 ping h2
PING 192.168.0.2 (192.168.0.2) 56(84) bytes of data.
64 bytes from 192.168.0.2: icmp_seq=1 ttl=64 time=200 ms
64 bytes from 192.168.0.2: icmp_seq=2 ttl=64 time=0.719 ms
64 bytes from 192.168.0.2: icmp_seq=3 ttl=64 time=0.093 ms
64 bytes from 192.168.0.2: icmp_seq=4 ttl=64 time=0.125 ms
64 bytes from 192.168.0.2: icmp_seq=5 ttl=64 time=0.095 ms
64 bytes from 192.168.0.2: icmp_seq=6 ttl=64 time=0.124 ms
64 bytes from 192.168.0.2: icmp_seq=7 ttl=64 time=0.106 ms
64 bytes from 192.168.0.2: icmp_seq=8 ttl=64 time=0.100 ms
64 bytes from 192.168.0.2: icmp_seq=9 ttl=64 time=0.099 ms
64 bytes from 192.168.0.2: icmp_seq=10 ttl=64 time=0.095 ms
64 bytes from 192.168.0.2: icmp_seq=11 ttl=64 time=0.110 ms
64 bytes from 192.168.0.2: icmp_seq=12 ttl=64 time=0.099 ms
64 bytes from 192.168.0.2: icmp_seq=13 ttl=64 time=0.102 ms
64 bytes from 192.168.0.2: icmp_seq=14 ttl=64 time=0.099 ms
64 bytes from 192.168.0.2: icmp_seq=15 ttl=64 time=0.096 ms
64 bytes from 192.168.0.2: icmp_seq=16 ttl=64 time=0.095 ms
64 bytes from 192.168.0.2: icmp_seq=17 ttl=64 time=0.098 ms
64 bytes from 192.168.0.2: icmp_seq=18 ttl=64 time=0.098 ms
64 bytes from 192.168.0.2: icmp_seq=19 ttl=64 time=0.117 ms
64 bytes from 192.168.0.2: icmp_seq=20 ttl=64 time=0.103 ms
64 bytes from 192.168.0.2: icmp_seq=21 ttl=64 time=0.104 ms
64 bytes from 192.168.0.2: icmp_seq=22 ttl=64 time=0.127 ms
64 bytes from 192.168.0.2: icmp_seq=23 ttl=64 time=0.100 ms
64 bytes from 192.168.0.2: icmp_seq=24 ttl=64 time=0.095 ms
64 bytes from 192.168.0.2: icmp_seq=25 ttl=64 time=0.097 ms
64 bytes from 192.168.0.2: icmp_seq=26 ttl=64 time=0.104 ms