Docs for named veths + troubleshooting

Partial-bug: 1491440

Change-Id: I43d501f76ef4acff954e564f5fd33d1779bfcbd2
(cherry picked from commit eb311fd086)

doc/source/install-guide/ops-troubleshooting-containernetworking.rst

@@ -0,0 +1,67 @@
+`Home <index.html>`__ OpenStack Ansible Installation Guide
+
+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:
+
+   .. code-block:: bash
+
+    ${CONTAINER_UNIQUE_ID}_${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:
+
+   .. code-block:: bash
+
+    $ 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.
+
+--------------
+
+.. include:: navigation.txt

doc/source/install-guide/ops-troubleshooting.rst

@@ -0,0 +1,12 @@
+`Home <index.html>`__ OpenStack Ansible Installation Guide
+
+Troubleshooting
+---------------
+
+.. toctree::
+
+   ops-troubleshooting-containernetworking.rst
+
+--------------
+
+.. include:: navigation.txt

doc/source/install-guide/ops.rst

@@ -7,6 +7,7 @@ Chapter 9. Operations
 
    ops-addcomputehost.rst
    ops-galera.rst
+   ops-troubleshooting.rst
 
 
 The following operations apply to environments after initial