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


    v6host1 [ label="IPv6 only host"];
    v6host2 [ label="IPv6 only host"];
    v6host3 [ label="IPv6 only host"];
    v6router [ label="IPv6 router"];

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

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

    v6host1--switch1;
    v6host2--switch1;
    v6host3--switch1;

    switch1--v6router;
    v6router--v4internet;
    v6router--v6internet;

}