In other commands, the name or ID of an object is just the name
of the object. For example, name or ID of a server is "server",
router is "router". So, do not use "identifier" in network commands.
Also, the parameter in doc file network.rst is not "identifier",
but "network".
Change-Id: I1ec3beefbb878a207bca280b994ca176ef04ee2d