graph template {
    label="ospf_topo2";
    splines = "line"

    # Routers
    r1 [
        shape=doubleoctagon,
        label="r1\n192.0.2.1\n2001:db8::1",
        fillcolor="#f08080",
        style=filled,
    ];
    r2 [
        shape=doubleoctagon,
        label="r2\n\192.0.2.2\n2001:db8::2",
        fillcolor="#f08080",
        style=filled,
    ];
    r3 [
        shape=doubleoctagon,
        label="r3\n192.0.2.3\n2001:db8::3",
        fillcolor="#f08080",
        style=filled,
    ];
    r4 [
        shape=doubleoctagon,
        label="r4\n192.0.2.4\n2001:db8::4",
        fillcolor="#f08080",
        style=filled,
    ];

    # Connections
    r1 -- r2 [label="eth1"];
    r1 -- r2 [label="eth2"];

    r2 -- r3 [label="eth3\neth1"];
    r1 -- r4 [label="eth3\neth1"];

    r4 -- r3 [label="eth2"];
    r4 -- r3 [label="eth3"];

    # Group r1 and r2 above, r3 and r4 below
    { rank=min; r1; r2; }
    { rank=max; r3; r4; }
}