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Container networking issues
All LXC containers on the host have two virtual ethernet interfaces:
- eth0 in the container connects to lxcbr0 on the host
- eth1 in the container connects to br-mgmt on the host
Note
Some containers, such as cinder, glance, neutron_agents, and swift_proxy, have more than two interfaces to support their functions.`
Predictable interface naming
On the host, all virtual ethernet devices are named based on their container as well as the name of the interface inside the container:
${CONTAINER_UNIQUE_ID}_${NETWORK_DEVICE_NAME}
As an example, an all-in-one (AIO) build might provide a utility container called aio1_utility_container-d13b7132. That container will have two network interfaces: d13b7132_eth0 and d13b7132_eth1.
Another option would be to use LXC's tools to retrieve information about the utility container:
$ lxc-info -n aio1_utility_container-d13b7132 Name: aio1_utility_container-d13b7132 State: RUNNING PID: 8245 IP: 10.0.3.201 IP: 172.29.237.204 CPU use: 79.18 seconds BlkIO use: 678.26 MiB Memory use: 613.33 MiB KMem use: 0 bytes Link: d13b7132_eth0 TX bytes: 743.48 KiB RX bytes: 88.78 MiB Total bytes: 89.51 MiB Link: d13b7132_eth1 TX bytes: 412.42 KiB RX bytes: 17.32 MiB Total bytes: 17.73 MiB
The Link: lines will show the network interfaces that
are attached to the utility container.
Reviewing container networking traffic
You can dump traffic on the br-mgmt bridge with
tcpdump to see all communications between various
containers, but you can narrow your focus by running
tcpdump only on the network interfaces of the containers
which are experiencing a problem.