digraph G {
    rankdir = LR;
    OsmoBTS -> OsmoBSC [label="Abis/IP"];
    OsmoBSC -> OsmoMSC [label="3GPP AoIP"];
    OsmoBSC -> OsmoMGW [label="MGCP"];
    OsmoBTS -> OsmoMGW [label="RTP",dir=both];
    OsmoMGW -> OsmoMSC [label="RTP",dir=both];
    {rank=same OsmoBSC OsmoMGW}
    OsmoMGW [color=red];
}