title: How to support multicast network in Docker
body: <p>I've met a big problem about the network configuration in docker. The senario is this:</p>
  
  <p>1.I have two eth on my serve : eth0 and eth1:</p>
  
  <pre><code>eth0: flags=4163&lt;UP,BROADCAST,RUNNING,MULTICAST&gt; mtu 1500
  inet 172.17.198.172 netmask 255.255.255.0 broadcast 172.17.198.255
  inet6 fe80::250:56ff:fea8:233f prefixlen 64 scopeid 0x20
  ether 00:50:56:a8:23:3f txqueuelen 1000 (Ethernet)
  RX packets 5415657 bytes 2659904664 (2.4 GiB)
  RX errors 0 dropped 78 overruns 0 frame 0
  TX packets 935762 bytes 1824232555 (1.6 GiB)
  TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
  
  eth1: flags=4163&lt;UP,BROADCAST,RUNNING,MULTICAST&gt; mtu 1500
  inet 10.251.6.68 netmask 255.255.255.0 broadcast 10.251.6.255
  inet6 fe80::250:56ff:fea8:1778 prefixlen 64 scopeid 0x20
  ether 00:50:56:a8:17:78 txqueuelen 1000 (Ethernet)
  RX packets 4954017171 bytes 349830337818 (325.8 GiB)
  RX errors 0 dropped 0 overruns 0 frame 0
  TX packets 66380998 bytes 4647495138 (4.3 GiB)
  TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
  </code></pre>
  
  <p>2.The eth0 is the default network interface. And eth1 is an interface which support multicast. It receives and send messages under the multicast mode.</p>
  
  <p>3.Now I create a container using following command:
  docker run -it -p 8181:8181 centos bash</p>
  
  <p>4.As my understanding, the eth0 and eth1 two interface will all be bridged to veth0 in the container. So my question is:</p>
  
  <p>&lt;1>If the eth0 and eth1 are all bridge to veth0, how the veth0 receive ip data package from two eths(eth0 and eth1)
  &lt;2>If my understanding is wrong, the docker only bridges eth0 to veth0. How can I bridge the eth1 to veth1 inside container so that the container could receive the multicast data packages from physical network through eth1 to veth1.
  Thanks so much ! This problem has been stucked me for a long long time. If you have any idea or any question, please leave a comment here. Thanks!</p>