Physical network diagram generated from dot config language

Is there a good and easy solution to automatically generate logical or physical network diagrams? Trying answer this question I've been playing today with the dot configuration language to test it in the field.

Automatically generated diagram

The DOT config file 

graph physical_net_topology {
 
legend [ label="{ legend | {red | public} |{blue| v1002 inside} | {green | v105 dmz} }", shape=record];


subgraph cluster_sp {
    label="pub switch";

    graph [ fillcolor="burlywood", style="filled"]
    node [shape=record,fillcolor="white", style="filled"]
    edge[style=invis];
    
    node [label="3"] p3 ;
    node [label="2"] p2 ;
    node [label="1"] p1 ;

    { rank=same; p1; p2; p3}
    p1 -- p2 -- p3;
}

subgraph cluster_si {
    label="Internal switch";

    edge[style=invis];
    node [shape=record ];

    node [label="1"] e1 ;
    node [label="2"] e2 ;
    node [label="3"] e3 ;
    node [label="4"] e4 ;
    node [label="5"] e5 ;
    node [label="6"] e6 ;

    { rank=same; e1; e2; e3; e4; e5; e6;}
    e1 -- e2 -- e3 -- e4 -- e5 -- e6;
}

subgraph cluster_fw1 {
    label="FW1 ports";

    graph = [ style = rounded]
    edge[style=invis]
    
    node [shape=record ];
    node [label="1"] f1 ;
    node [label="2"] f2 ;
    node [label="3"] f3 ;
    node [label="4"] f4 ;

  { rank=same; f1; f2; f3; f4; }

  f1 -- f2 -- f3 -- f4'
}

p2 -- f1 [color="red"]
f2 -- e1 [color="blue"]
f3 -- e2 [color="green"]

e3 -- server1 [color="green"]
e4 -- server2 [color="green"]
e6 -- server3 [color="blue"]

}

Results discussion

It took me a good couple of hours to write this config. Even after that I still have only a very basic understanding of how flexible the dot language is. The coding was very laborious. It required a lot of trying and testing if the new generated graph is what you are looking for.

Often the options I was trying didn't have any effect.

The documentation I found and read wasn't explaining all the details so trying and intuition was often your only friend.

References

http://sandbox.kidstrythisathome.com/erdos/
http://graphviz-dev.appspot.com/
http://www.graphviz.org/

http://rtomaszewski.blogspot.co.uk/search/label/diagram