Testando o ping entre os containers:

root@docker-ubuntu-1:/# ping 172.16.42.20
PING 172.16.42.20 (172.16.42.20) 56(84) bytes of data.
64 bytes from 172.16.42.20: icmp_seq=1 ttl=64 time=3.34 ms
64 bytes from 172.16.42.20: icmp_seq=2 ttl=64 time=0.354 ms
64 bytes from 172.16.42.20: icmp_seq=3 ttl=64 time=1.02 ms
^C
--- 172.16.42.20 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2001ms
rtt min/avg/max/mdev = 0.354/1.575/3.345/1.281 ms

root@docker-ubuntu-2:/# ping 172.16.42.10
PING 172.16.42.10 (172.16.42.10) 56(84) bytes of data.
64 bytes from 172.16.42.10: icmp_seq=1 ttl=64 time=1.48 ms
64 bytes from 172.16.42.10: icmp_seq=2 ttl=64 time=14.8 ms
64 bytes from 172.16.42.10: icmp_seq=3 ttl=64 time=0.533 ms
^C
--- 172.16.42.10 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2003ms
rtt min/avg/max/mdev = 0.533/5.620/14.846/6.535 ms

Com o comando ovs-vsctp show, é possível verificar as configurações de todas as Bridges.

[root@docker-centos6-5-srv1 docker]# ovs-vsctl show
fc82c710-a114-4d3a-952d-21bd0cdb3925
  Bridge "br0"
    Port "gre0"
      Interface "gre0"
        type: gre
        options: {remote_ip="192.168.0.229"}
    Port "br0"
      Interface "br0"
        type: internal
  ovs_version: "2.3.1"

[root@docker-centos6-5-srv2 docker]# ovs-vsctl show
347c8fc0-98a1-4749-99d8-b2b7c40acdff
  Bridge "br0"
    Port "br0"
      Interface "br0"
        type: internal
    Port "gre0"
      Interface "gre0"
        type: gre
        options: {remote_ip="192.168.0.227"}
  ovs_version: "2.3.1"

Continua...

Fonte

• Open vSwitch
• Multi-Host Docker Network | Wiredcraft
• Docker: Tutorial mão na massa
• As baleias na Nuvem: entenda como funciona o Docker -
• A Gentle Introduction To Docker And All Things Containers
• Docker: containers, isolamento e replicabilidade de ambientes de produção | Um Manifesto!

Mais sobre Docker, visite o meu blog: http://tutoriaisgnulinux.com