doc: explain rpf lookup default mode
Reported-by: Alexis Rosen <quagga-users@alexis.users.panix.com>
Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
diff --git a/doc/main.texi b/doc/main.texi
index 810866a..4c11d24 100644
--- a/doc/main.texi
+++ b/doc/main.texi
@@ -224,6 +224,11 @@
Multicast RIB takes precedence.
@end table
+The @code{mrib-then-urib} setting is the default behavior if nothing is
+configured. If this is the desired behavior, it should be explicitly
+configured to make the configuration immune against possible changes in
+what the default behavior is.
+
WARNING: Unreachable routes do not receive special treatment and do not
cause fallback to a second lookup.
@end deffn