doc: Add description about 6to4 tunnelling.

diff --git a/doc/service-api.txt b/doc/service-api.txt
index 65554a2..7e87e6e 100644 (file)
--- a/doc/service-api.txt
+++ b/doc/service-api.txt
@@ -347,12 +347,16 @@ Properties        string State [readonly]
 
                        string Method [readonly]
 
-                               Possible values are "auto", "manual"
+                               Possible values are "auto", "manual", "6to4"
                                and "off".
 
                                The value "fixed" indicates an IP address
                                that can not be modified. For example
                                cellular networks return fixed information.
+                               The value "6to4" is returned if 6to4 tunnel
+                               is created by connman. The tunnel can only be
+                               created if method was set to "auto" by the
+                               user. User cannot set the method to "6to4".
 
                        string Address [readonly]