How to support multicast network in Docker

docker networking containers multicast bridge
Kisen.Chin picture Kisen.Chin · Aug 8, 2018 · Viewed 9.2k times · Source

I've met a big problem about the network configuration in docker. The senario is this:

1.I have two eth on my serve : eth0 and eth1:

eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> 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<UP,BROADCAST,RUNNING,MULTICAST> 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

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.

3.Now I create a container using following command: docker run -it -p 8181:8181 centos bash

4.As my understanding, the eth0 and eth1 two interface will all be bridged to veth0 in the container. So my question is:

<1>If the eth0 and eth1 are all bridge to veth0, how the veth0 receive ip data package from two eths(eth0 and eth1) <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!

Answer

BMitch picture BMitch · Aug 8, 2018

I don't believe this is currently supported. Best option may be to disable Docker's network namespacing and use --net host. Note that this gives the container direct access to the host interfaces, and you'll need to connect through published ports to access others containers.

You can follow the current status with this issue: https://github.com/moby/moby/issues/23659

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