doc: inform the diff between config from zebra and outside

To avoid some confusions, it is precised in the documentation that
the configuration not done from zebra will not be injected in the
configuration context. As consequence, the config file will not be
impacted by underlying network context. But also, this will not be
possible for *Zebra* to attempt to modify outside networking objects.

Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>

diff --git a/doc/user/zebra.rst b/doc/user/zebra.rst
index 9e377330ee7bf60c742baff44688e6eee6b24a01..d28669506388daf2eb301ad3ffd39273e98be516 100644 (file)
--- a/doc/user/zebra.rst
+++ b/doc/user/zebra.rst
@@ -58,6 +58,26 @@ Besides the common invocation options (:ref:`common-invocation-options`), the
 
 .. _interface-commands:
 
+Configuration Addresses behaviour
+=================================
+
+At startup, *Zebra* will first discover the underlying networking objects
+from the operating system. This includes interfaces, addresses of
+interfaces, static routes, etc. Then, it will read the configuration
+file, including its own interface addresses, static routes, etc. All this
+information comprises the operational context from *Zebra*. But
+configuration context from *Zebra* will remain the same as the one from
+:file:`zebra.conf` config file. As an example, executing the following
+:clicmd:`show running-config` will reflect what was in :file:`zebra.conf`.
+In a similar way, networking objects that are configured outside of the
+*Zebra* like *iproute2* will not impact the configuration context from
+*Zebra*. This behaviour permits you to continue saving your own config
+file, and decide what is really to be pushed on the config file, and what
+is dependent on the underlying system.
+Note that inversely, from *Zebra*, you will not be able to delete networking
+objects that were previously configured outside of *Zebra*.
+
+
 Interface Commands
 ==================