Parameters for transit_stub topology by itm:

-stubs_per_transit [number of stubs per transit node] (default = 3)
-ts_extra_edges [number of extra transit-stub edges] (default = 0)
-ss_extra_edges [number of extra stub-stub edges] (default = 0) 

-transit_domains [number of transit domains] (default = 1)
-domains_scale [top level scale used by ITM] (default = 20)

* Connectivity of domains [similar to the random topology parameters]
-domains_method (default = pure-random)
-domains_connection_prob (default = 1.0) [fully connected]
-domains_beta (default = 0.5)
-domains_gamma (default = 0.5)

* Connectivity of transit nodes:
-transit_nodes (default = 4)
-transit_scale (default = 20)
-transit_method (default = pure-random)
-transit_connection_prob (default = 0.6)
-transit_beta (default = 0.5)
-transit_gamma (default = 0.5)

* Connectivity of stub nodes:
-stub_nodes (default = 8)
-stub_method (default = pure-random)
-stub_connection_prob (default = 0.4)
-stub_beta (default = 0.5)
-stub_gamma (default = 0.5)

* Total number of nodes is computed as follows:      
 nodes=transit_domains * transit_nodes * (1 + stubs_per_transit * stub_nodes)

 for example, for the above default settings we get:
        1 * 4 ( 1 + 3 * 8 ) = 100 nodes