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Merge "cleanup of network troubleshooting rst file in ops-guide"

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doc/ops-guide/source/ops_network_troubleshooting.rst
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@ -2,13 +2,12 @@
Network Troubleshooting
=======================
Network troubleshooting can unfortunately be a very difficult and
confusing procedure. A network issue can cause a problem at several
points in the cloud. Using a logical troubleshooting procedure can help
mitigate the confusion and more quickly isolate where exactly the
network issue is. This chapter aims to give you the information you need
to identify any issues for either ``nova-network`` or OpenStack
Networking (neutron) with Linux Bridge or Open vSwitch.
Network troubleshooting can be challenging. A network issue may cause
problems at any point in the cloud. Using a logical troubleshooting
procedure can help mitigate the issue and isolate where the network issue is.
This chapter aims to give you the information you need to identify any
issues for ``nova-network`` or OpenStack Networking (neutron) with Linux
Bridge or Open vSwitch.
Using "ip a" to Check Interface States
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@ -21,9 +20,8 @@ IPs, VLANs, and whether your interfaces are up:
# ip a
If you're encountering any sort of networking difficulty, one good
initial sanity check is to make sure that your interfaces are up. For
example:
If you are encountering any sort of networking difficulty, one good initial
troubleshooting step is to make sure that your interfaces are up. For example:
.. code-block:: console
@ -42,8 +40,8 @@ created by libvirt and not used by OpenStack.
Visualizing nova-network Traffic in the Cloud
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
If you are logged in to an instance and ping an external host—for
example, Google—the ping packet takes the route shown in
If you are logged in to an instance and ping an external host, for
example, Google, the ping packet takes the route shown in
:ref:`figure_traffic_route`.
.. _figure_traffic_route:
@ -108,9 +106,8 @@ environment.
For this example, we will use the Open vSwitch (OVS) back end. Other
back-end plug-ins will have very different flow paths. OVS is the most
popularly deployed network driver, according to the October 2015
OpenStack User Survey, with 41 percent more sites using it than the
Linux Bridge driver. We'll describe each step in turn, with
popularly deployed network driver, according to the April 2016
OpenStack User Survey. We'll describe each step in turn, with
:ref:`network_paths` for reference.
#. The instance generates a packet and places it on the virtual NIC
@ -475,7 +472,7 @@ One great, although very in-depth, way of troubleshooting network issues
is to use ``tcpdump``. We recommended using ``tcpdump`` at several
points along the network path to correlate where a problem might be. If
you prefer working with a GUI, either live or by using a ``tcpdump``
capture, do also check out
capture, check out
`Wireshark <http://www.wireshark.org/>`_.
For example, run the following command:
@ -623,7 +620,7 @@ Manually Disassociating a Floating IP
-------------------------------------
Sometimes an instance is terminated but the floating IP was not
correctly de-associated from that instance. Because the database is in
correctly disassociated from that instance. Because the database is in
an inconsistent state, the usual tools to disassociate the IP no longer
work. To fix this, you must manually update the database.
@ -986,7 +983,7 @@ each compute and network node in your cluster:
.
gre-<N>
If any of these links is missing or incorrect, it suggests a
If any of these links are missing or incorrect, it suggests a
configuration error. Bridges can be added with ``ovs-vsctl add-br``,
and ports can be added to bridges with
``ovs-vsctl add-port``. While running these by hand can be useful
@ -1060,7 +1057,7 @@ Summary
The authors have spent too much time looking at packet dumps in order to
distill this information for you. We trust that, following the methods
outlined in this chapter, you will have an easier time! Aside from
outlined in this chapter, you will have an easier time. Aside from
working with the tools and steps above, don't forget that sometimes an
extra pair of eyes goes a long way to assist.