graph G {
    node [ shape="box"];


    v4host1 [ label="IPv4 only host"];
    v4host2 [ label="IPv4 only host"];
    v4host3 [ label="IPv4 only host"];
    v4router [ label="IPv4 router"];

    v4internet [ label="IPv4 Internet", shape="egg" ];
    v6internet [ label="IPv6 Internet", shape="egg" ];


    switch1 [ label="Network Switch", shape="oval" ];

    v4host1--switch1;
    v4host2--switch1;
    v4host3--switch1;

    switch1--v4router;

    v4router--v4internet;
    v4router--v6internet;

}
