graph {
    rankdir=TD
    graph [splines=ortho]
    Switch -- "Internet"
    Switch -- { "4. Thinclient"; "3. Thinclient"; "2. Thinclient"; "1. Thinclient"} [color="red"]
    VBridge -- Switch
    Switch -- FiSiNetz
    subgraph cluster_physisch {
        graph[style=dotted, color="red"]
        "4. Thinclient" [color="red"]
        "3. Thinclient" [color="red"]
        "2. Thinclient" [color="red"]
        "1. Thinclient" [color="red"]
    }
    subgraph cluster_vlan {
        graph[style=dotted]
        Zeus -- VBridge
        Poseidon -- VBridge [color="red"]
        Hades -- VBridge
        Poseidon [color="red"]
    }
}