For ______ service, we need a virtual-circuit subnet. Let us see how that works. The idea behind virtual circuits is to avoid having to choose a new ______ for every packet sent. Instead,when a connection is established, a route from the ______ machine to the destination machine ischosen as part of the connection setup and stored in tables inside the ______. That route is used forall traffic flowing over the connection, exactly the same way that the telephone system works.When the connection is released, the virtual circuit is also terminateD、With connection-orientedservice, each packet carries an ______ telling which virtual circuit it belongs to.